diff --git a/array.c b/array.c
index 76a3a6279db15d..522da842a05280 100644
--- a/array.c
+++ b/array.c
@@ -1320,6 +1320,9 @@ rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
+ *     ary.find_index(obj)             ->  int or nil
+ *     ary.find_index { |item| block } ->  int or nil
+ *     ary.find_index                  ->  Enumerator
  *     ary.index(obj)             ->  int or nil
  *     ary.index { |item| block } ->  int or nil
  *     ary.index                  ->  Enumerator
diff --git a/bignum.c b/bignum.c
index b2daac75af6088..1b9d184df8be2f 100644
--- a/bignum.c
+++ b/bignum.c
@@ -3761,6 +3761,7 @@ rb_big_coerce(VALUE x, VALUE y)
 /*
  *  call-seq:
  *     big.abs -> aBignum
+ *     big.magnitude -> aBignum
  *
  *  Returns the absolute value of <i>big</i>.
  *
diff --git a/complex.c b/complex.c
index f6f63f6ebd1c2d..19c20b356553e1 100644
--- a/complex.c
+++ b/complex.c
@@ -2018,6 +2018,7 @@ numeric_arg(VALUE self)
 /*
  * call-seq:
  *    num.rect  ->  array
+ *    num.rectangular  ->  array
  *
  * Returns an array; [num, 0].
  */
diff --git a/dir.c b/dir.c
index 4322344e6bf3d0..33ab7f8ab1de9b 100644
--- a/dir.c
+++ b/dir.c
@@ -544,6 +544,7 @@ dir_inspect(VALUE dir)
 /*
  *  call-seq:
  *     dir.path -> string or nil
+ *     dir.to_path -> string or nil
  *
  *  Returns the path parameter passed to <em>dir</em>'s constructor.
  *
@@ -732,7 +733,7 @@ dir_seek(VALUE dir, VALUE pos)
 
 /*
  *  call-seq:
- *     dir.pos( integer ) -> integer
+ *     dir.pos = integer  -> integer
  *
  *  Synonym for <code>Dir#seek</code>, but returns the position
  *  parameter.
diff --git a/encoding.c b/encoding.c
index 0c92dfedef83d0..3d89d52ea62841 100644
--- a/encoding.c
+++ b/encoding.c
@@ -992,6 +992,7 @@ enc_inspect(VALUE self)
 /*
  * call-seq:
  *   enc.name -> string
+ *   enc.to_s -> string
  *
  * Returns the name of the encoding.
  *
diff --git a/enumerator.c b/enumerator.c
index 3aa0d2ea783c22..44c574728b199f 100644
--- a/enumerator.c
+++ b/enumerator.c
@@ -526,6 +526,8 @@ enumerator_with_object_i(VALUE val, VALUE memo, int argc, VALUE *argv)
 
 /*
  * call-seq:
+ *   e.each_with_object(obj) {|(*args), obj| ... }
+ *   e.each_with_object(obj)
  *   e.with_object(obj) {|(*args), obj| ... }
  *   e.with_object(obj)
  *
@@ -1501,6 +1503,7 @@ lazy_flat_map_func(VALUE val, VALUE m, int argc, VALUE *argv)
 
 /*
  *  call-seq:
+ *     lazy.collect_concat { |obj| block } -> a_lazy_enumerator
  *     lazy.flat_map       { |obj| block } -> a_lazy_enumerator
  *
  *  Returns a new lazy enumerator with the concatenated results of running
diff --git a/ext/date/date_core.c b/ext/date/date_core.c
index 914b81eeaa7a72..45c136c234c34f 100644
--- a/ext/date/date_core.c
+++ b/ext/date/date_core.c
@@ -5935,6 +5935,7 @@ d_lite_prev_day(int argc, VALUE *argv, VALUE self)
 
 /*
  * call-seq:
+ *    d.succ  ->  date
  *    d.next  ->  date
  *
  * Returns a date object denoting the following day.
diff --git a/ext/dbm/dbm.c b/ext/dbm/dbm.c
index 57d227e8ad7c81..27ade017e16df5 100644
--- a/ext/dbm/dbm.c
+++ b/ext/dbm/dbm.c
@@ -655,6 +655,7 @@ fdbm_store(VALUE obj, VALUE keystr, VALUE valstr)
 /*
  * call-seq:
  *   dbm.length -> integer
+ *   dbm.size -> integer
  *
  * Returns the number of entries in the database.
  */
@@ -832,7 +833,10 @@ fdbm_values(VALUE obj)
 
 /*
  * call-seq:
+ *   dbm.include?(key) -> boolean
  *   dbm.has_key?(key) -> boolean
+ *   dbm.member?(key) -> boolean
+ *   dbm.key?(key) -> boolean
  *
  * Returns true if the database contains the specified key, false otherwise.
  */
@@ -859,6 +863,7 @@ fdbm_has_key(VALUE obj, VALUE keystr)
 /*
  * call-seq:
  *   dbm.has_value?(value) -> boolean
+ *   dbm.value?(value) -> boolean
  *
  * Returns true if the database contains the specified string value, false
  * otherwise.
diff --git a/ext/dl/cfunc.c b/ext/dl/cfunc.c
index 2a96b30bed43dc..b68129f8ed0f29 100644
--- a/ext/dl/cfunc.c
+++ b/ext/dl/cfunc.c
@@ -285,7 +285,9 @@ rb_dlcfunc_set_ptr(VALUE self, VALUE addr)
 }
 
 /*
- * call-seq: inspect
+ * call-seq:
+ *    inspect
+ *    to_s
  *
  * Returns a string formatted with an easily readable representation of the
  * internal state of the DL::CFunc
diff --git a/ext/gdbm/gdbm.c b/ext/gdbm/gdbm.c
index 9d958d54a28183..45ed9594a73855 100644
--- a/ext/gdbm/gdbm.c
+++ b/ext/gdbm/gdbm.c
@@ -953,7 +953,9 @@ fgdbm_values(VALUE obj)
 
 /*
  * call-seq:
+ *      gdbm.include?(k) -> true or false
  *      gdbm.has_key?(k) -> true or false
+ *      gdbm.member?(k) -> true or false
  *      gdbm.key?(k) -> true or false
  *
  * Returns true if the given key _k_ exists within the database.
diff --git a/ext/io/wait/wait.c b/ext/io/wait/wait.c
index c7a290fd4f236f..d8bb55fc475fe0 100644
--- a/ext/io/wait/wait.c
+++ b/ext/io/wait/wait.c
@@ -96,6 +96,8 @@ io_ready_p(VALUE io)
  * call-seq:
  *   io.wait          -> IO, true, false or nil
  *   io.wait(timeout) -> IO, true, false or nil
+ *   io.wait_readable          -> IO, true, false or nil
+ *   io.wait_readable(timeout) -> IO, true, false or nil
  *
  * Waits until input is available or times out and returns self or nil when
  * EOF is reached.
diff --git a/ext/json/generator/generator.c b/ext/json/generator/generator.c
index ae4593c940f41f..42a16588113b9d 100644
--- a/ext/json/generator/generator.c
+++ b/ext/json/generator/generator.c
@@ -1178,11 +1178,11 @@ static VALUE cState_array_nl_set(VALUE self, VALUE array_nl)
 
 
 /*
-* call-seq: check_circular?
-*
-* Returns true, if circular data structures should be checked,
-* otherwise returns false.
-*/
+ * call-seq: check_circular?
+ *
+ * Returns true, if circular data structures should be checked,
+ * otherwise returns false.
+ */
 static VALUE cState_check_circular_p(VALUE self)
 {
     GET_STATE(self);
diff --git a/ext/openssl/ossl_hmac.c b/ext/openssl/ossl_hmac.c
index 5220c9e73d3b1c..d30d04ec670a14 100644
--- a/ext/openssl/ossl_hmac.c
+++ b/ext/openssl/ossl_hmac.c
@@ -206,7 +206,7 @@ ossl_hmac_s_digest(VALUE klass, VALUE digest, VALUE key, VALUE data)
 
 /*
  *  call-seq:
- *     HMAC.digest(digest, key, data) -> aString
+ *     HMAC.hexdigest(digest, key, data) -> aString
  *
  */
 static VALUE
diff --git a/ext/openssl/ossl_ocsp.c b/ext/openssl/ossl_ocsp.c
index e82c2d859a709b..4e2e8394a41cc5 100644
--- a/ext/openssl/ossl_ocsp.c
+++ b/ext/openssl/ossl_ocsp.c
@@ -149,7 +149,7 @@ ossl_ocspreq_add_nonce(int argc, VALUE *argv, VALUE self)
  *  2: nonces both absent.
  *  3: nonce present in response only.
  *  0: nonces both present and not equal.
- * -1: nonce in request only.
+ *  -1: nonce in request only.
  *
  *  For most responders clients can check return > 0.
  *  If responder doesn't handle nonces return != 0 may be
diff --git a/ext/openssl/ossl_pkey_dh.c b/ext/openssl/ossl_pkey_dh.c
index c8fb40e1ff05d5..a6ae0063f5b338 100644
--- a/ext/openssl/ossl_pkey_dh.c
+++ b/ext/openssl/ossl_pkey_dh.c
@@ -278,7 +278,9 @@ ossl_dh_is_private(VALUE self)
 
 /*
  *  call-seq:
+ *     dh.export -> aString
  *     dh.to_pem -> aString
+ *     dh.to_s -> aString
  *
  * Encodes this DH to its PEM encoding. Note that any existing per-session
  * public/private keys will *not* get encoded, just the Diffie-Hellman
@@ -428,7 +430,7 @@ ossl_dh_to_public_key(VALUE self)
 
 /*
  *  call-seq:
- *     dh.check_params -> true | false
+ *     dh.params_ok? -> true | false
  *
  * Validates the Diffie-Hellman parameters associated with this instance.
  * It checks whether a safe prime and a suitable generator are used. If this
diff --git a/ext/openssl/ossl_pkey_dsa.c b/ext/openssl/ossl_pkey_dsa.c
index ba28ba028d74e4..823b9b66e5a958 100644
--- a/ext/openssl/ossl_pkey_dsa.c
+++ b/ext/openssl/ossl_pkey_dsa.c
@@ -291,7 +291,9 @@ ossl_dsa_is_private(VALUE self)
 
 /*
  *  call-seq:
+ *    dsa.export([cipher, password]) -> aString
  *    dsa.to_pem([cipher, password]) -> aString
+ *    dsa.to_s([cipher, password]) -> aString
  *
  * Encodes this DSA to its PEM encoding.
  *
diff --git a/ext/openssl/ossl_pkey_ec.c b/ext/openssl/ossl_pkey_ec.c
index 8e6d88f60609b3..9d7607ef2f80ad 100644
--- a/ext/openssl/ossl_pkey_ec.c
+++ b/ext/openssl/ossl_pkey_ec.c
@@ -533,8 +533,8 @@ static VALUE ossl_ec_key_to_string(VALUE self, VALUE ciph, VALUE pass, int forma
 
 /*
  *  call-seq:
- *     key.export   => String
- *     key.export(cipher, pass_phrase) => String
+ *     key.export([cipher, pass_phrase]) => String
+ *     key.to_pem([cipher, pass_phrase]) => String
  *
  * Outputs the EC key in PEM encoding.  If +cipher+ and +pass_phrase+ are
  * given they will be used to encrypt the key.  +cipher+ must be an
@@ -843,6 +843,7 @@ static VALUE ossl_ec_group_initialize(int argc, VALUE *argv, VALUE self)
 }
 
 /*  call-seq:
+ *     group1.eql?(group2)   => true | false
  *     group1 == group2   => true | false
  *
  */
@@ -1312,6 +1313,7 @@ static VALUE ossl_ec_point_initialize(int argc, VALUE *argv, VALUE self)
 
 /*
  *  call-seq:
+ *     point1.eql?(point2) => true | false
  *     point1 == point2 => true | false
  *
  */
diff --git a/ext/openssl/ossl_pkey_rsa.c b/ext/openssl/ossl_pkey_rsa.c
index e395e7108f3149..4c346a042fdcc0 100644
--- a/ext/openssl/ossl_pkey_rsa.c
+++ b/ext/openssl/ossl_pkey_rsa.c
@@ -291,8 +291,9 @@ ossl_rsa_is_private(VALUE self)
 
 /*
  * call-seq:
- *   rsa.to_pem                      => PEM-format String
- *   rsa.to_pem(cipher, pass_phrase) => PEM-format String
+ *   rsa.export([cipher, pass_phrase]) => PEM-format String
+ *   rsa.to_pem([cipher, pass_phrase]) => PEM-format String
+ *   rsa.to_s([cipher, pass_phrase]) => PEM-format String
  *
  * Outputs this keypair in PEM encoding.  If +cipher+ and +pass_phrase+ are
  * given they will be used to encrypt the key.  +cipher+ must be an
diff --git a/ext/openssl/ossl_ssl.c b/ext/openssl/ossl_ssl.c
index d5c07d79a9964c..e80a14802b5a1f 100644
--- a/ext/openssl/ossl_ssl.c
+++ b/ext/openssl/ossl_ssl.c
@@ -1627,7 +1627,7 @@ ossl_ssl_get_peer_cert_chain(VALUE self)
 
 /*
 * call-seq:
-*    ssl.version => String
+*    ssl.ssl_version => String
 *
 * Returns a String representing the SSL/TLS version that was negotiated
 * for the connection, for example "TLSv1.2".
diff --git a/ext/openssl/ossl_x509store.c b/ext/openssl/ossl_x509store.c
index 2afa0cf5956c4f..f59c376574fe07 100644
--- a/ext/openssl/ossl_x509store.c
+++ b/ext/openssl/ossl_x509store.c
@@ -257,7 +257,7 @@ ossl_x509store_add_path(VALUE self, VALUE dir)
 
 /*
  * call-seq:
- *   store.set_default_path
+ *   store.set_default_paths
  *
  * Adds the default certificates to the certificate store.  These certificates
  * are loaded from the default configuration directory which can usually be
diff --git a/ext/sdbm/init.c b/ext/sdbm/init.c
index 0fd837db3121de..4eee21573fe189 100644
--- a/ext/sdbm/init.c
+++ b/ext/sdbm/init.c
@@ -117,11 +117,11 @@ fsdbm_close(VALUE obj)
 }
 
 /*
-* call-seq:
-*   sdbm.closed? -> true or false
-*
-* Returns +true+ if the database is closed.
-*/
+ * call-seq:
+ *   sdbm.closed? -> true or false
+ *
+ * Returns +true+ if the database is closed.
+ */
 static VALUE
 fsdbm_closed(VALUE obj)
 {
@@ -142,20 +142,20 @@ fsdbm_alloc(VALUE klass)
     return Data_Wrap_Struct(klass, 0, free_sdbm, 0);
 }
 /*
-* call-seq:
-*   SDBM.new(filename, mode = 0666)
-*
-* Creates a new database handle by opening the given +filename+. SDBM actually
-* uses two physical files, with extensions '.dir' and '.pag'. These extensions
-* will automatically be appended to the +filename+.
-*
-* If the file does not exist, a new file will be created using the given
-* +mode+, unless +mode+ is explicitly set to nil. In the latter case, no
-* database will be created.
-*
-* If the file exists, it will be opened in read/write mode. If this fails, it
-* will be opened in read-only mode.
-*/
+ * call-seq:
+ *   SDBM.new(filename, mode = 0666)
+ *
+ * Creates a new database handle by opening the given +filename+. SDBM actually
+ * uses two physical files, with extensions '.dir' and '.pag'. These extensions
+ * will automatically be appended to the +filename+.
+ *
+ * If the file does not exist, a new file will be created using the given
+ * +mode+, unless +mode+ is explicitly set to nil. In the latter case, no
+ * database will be created.
+ *
+ * If the file exists, it will be opened in read/write mode. If this fails, it
+ * will be opened in read-only mode.
+ */
 static VALUE
 fsdbm_initialize(int argc, VALUE *argv, VALUE obj)
 {
diff --git a/ext/socket/option.c b/ext/socket/option.c
index e3e59cf0c52877..4f89c049a45314 100644
--- a/ext/socket/option.c
+++ b/ext/socket/option.c
@@ -127,6 +127,7 @@ sockopt_optname_m(VALUE self)
 /*
  * call-seq:
  *   sockopt.data => string
+ *   sockopt.to_s => string
  *
  * returns the socket option data as a string.
  *
diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index 26872e0978f30c..0aad063b5ed6e1 100644
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@@ -1331,6 +1331,8 @@ strio_read(int argc, VALUE *argv, VALUE self)
 /*
  * call-seq:
  *   strio.sysread(integer[, outbuf])    -> string
+ *   strio.readpartial(integer[, outbuf])    -> string
+ *   strio.read_nonblock(integer[, outbuf])    -> string
  *
  * Similar to #read, but raises +EOFError+ at end of string instead of
  * returning +nil+, as well as IO#sysread does.
@@ -1363,6 +1365,7 @@ strio_sysread(int argc, VALUE *argv, VALUE self)
 
 /*
  * call-seq:
+ *   strio.length -> integer
  *   strio.size   -> integer
  *
  * Returns the size of the buffer string.
diff --git a/ext/win32ole/win32ole.c b/ext/win32ole/win32ole.c
index 5310cbfae1f200..d42b53a8e029b0 100644
--- a/ext/win32ole/win32ole.c
+++ b/ext/win32ole/win32ole.c
@@ -5750,7 +5750,7 @@ ole_type_visible(ITypeInfo *pTypeInfo)
 
 /*
  *  call-seq:
- *    WIN32OLE_TYPE#visible  #=> true or false
+ *    WIN32OLE_TYPE#visible?  #=> true or false
  *
  *  Returns true if the OLE class is public.
  *    tobj = WIN32OLE_TYPE.new('Microsoft Excel 9.0 Object Library', 'Application')
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index e5a1e670f70441..64a3e697c63981 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -1293,12 +1293,8 @@ rb_zstream_finish(VALUE obj)
 
 /*
  * call-seq:
- *   flush_next_out                 -> String
- *   flush_next_out { |chunk| ... } -> nil
+ *   flush_next_in -> input
  *
- * Flushes output buffer and returns all data in that buffer.  If a block is
- * given each chunk is yielded to the block until the current output buffer
- * has been flushed.
  */
 static VALUE
 rb_zstream_flush_next_in(VALUE obj)
@@ -1313,7 +1309,13 @@ rb_zstream_flush_next_in(VALUE obj)
 }
 
 /*
- * Flushes output buffer and returns all data in that buffer.
+ * call-seq:
+ *   flush_next_out                 -> String
+ *   flush_next_out { |chunk| ... } -> nil
+ *
+ * Flushes output buffer and returns all data in that buffer.  If a block is
+ * given each chunk is yielded to the block until the current output buffer
+ * has been flushed.
  */
 static VALUE
 rb_zstream_flush_next_out(VALUE obj)
diff --git a/io.c b/io.c
index ce6dc70af78df8..e2a66ae57b7277 100644
--- a/io.c
+++ b/io.c
@@ -8378,10 +8378,7 @@ rb_io_advise(int argc, VALUE *argv, VALUE io)
 
 /*
  *  call-seq:
- *     IO.select(read_array
- *               [, write_array
- *               [, error_array
- *               [, timeout]]]) -> array  or  nil
+ *     IO.select(read_array[, write_array[, error_array[, timeout]]]) -> array or nil
  *
  *  Calls select(2) system call.
  *  It monitors given arrays of <code>IO</code> objects, waits one or more
diff --git a/numeric.c b/numeric.c
index 66820eeed1f1d1..d6cfc8d3127380 100644
--- a/numeric.c
+++ b/numeric.c
@@ -853,6 +853,7 @@ flo_div(VALUE x, VALUE y)
 
 /*
  *  call-seq:
+ *     float.fdiv(numeric)  ->  float
  *     float.quo(numeric)  ->  float
  *
  *  Returns float / numeric.
diff --git a/proc.c b/proc.c
index 4596003daf813c..9d083df269e637 100644
--- a/proc.c
+++ b/proc.c
@@ -1052,6 +1052,7 @@ mnew(VALUE klass, VALUE obj, ID id, VALUE mclass, int scope)
 
 /*
  * call-seq:
+ *   meth.eql?(other_meth)  -> true or false
  *   meth == other_meth  -> true or false
  *
  * Two method objects are equal if they are bound to the same
diff --git a/re.c b/re.c
index 16d7e3450ca874..fe7e3903b5c32f 100644
--- a/re.c
+++ b/re.c
@@ -2643,6 +2643,7 @@ match_hash(VALUE match)
 /*
  * call-seq:
  *    mtch == mtch2   -> true or false
+ *    mtch.eql?(mtch2)   -> true or false
  *
  *  Equality---Two matchdata are equal if their target strings,
  *  patterns, and matched positions are identical.
diff --git a/string.c b/string.c
index 8b85739e70b5cc..d9a91b5a6f2ed0 100644
--- a/string.c
+++ b/string.c
@@ -8032,6 +8032,7 @@ sym_casecmp(VALUE sym, VALUE other)
 /*
  * call-seq:
  *   sym =~ obj   -> fixnum or nil
+ *   sym.match(obj)   -> fixnum or nil
  *
  * Returns <code>sym.to_s =~ obj</code>.
  */
@@ -8045,7 +8046,9 @@ sym_match(VALUE sym, VALUE other)
 /*
  * call-seq:
  *   sym[idx]      -> char
- *   sym[b, n]     -> char
+ *   sym[b, n]     -> string
+ *   sym.slice(idx)      -> char
+ *   sym.slice(b, n)     -> string
  *
  * Returns <code>sym.to_s[]</code>.
  */
@@ -8059,6 +8062,7 @@ sym_aref(int argc, VALUE *argv, VALUE sym)
 /*
  * call-seq:
  *   sym.length    -> integer
+ *   sym.size    -> integer
  *
  * Same as <code>sym.to_s.length</code>.
  */