Middle English speken, from Old English specan, variant of sprecan "to utter words articulately without singing, have or use the power of speech; make a speech; hold discourse" with others (class V strong verb; past tense spræc, past participle sprecen), from Proto-Germanic *sprekanan (source also of Old Saxon sprecan, Old Frisian spreka, Middle Dutch spreken, Old High German sprehhan, German sprechen "to speak," Old Norse spraki "rumor, report"). This has sometimes been said to represent a PIE root meaning "to strew," on notion of speech as a "scattering" of words, but Boutkan finds no Indo-European etymology for the Germanic word.
In English the -r- began to drop out in Late West Saxon and was gone by mid-12c., perhaps from influence of Danish spage "crackle," also used in a slang sense of "speak" (compare crack (v.) in slang senses having to do with speech, such as wisecrack, cracker, all it's cracked up to be). Elsewhere, rare variant forms without -r- are found in Middle Dutch (speken), Old High German (spehhan), dialectal German (spächten "speak").
Apparently not the primary word for "to speak" in Old English (the "Beowulf" author prefers maþelian, from mæþel "assembly, council," from root of metan "to meet;" compare Greek agoreuo "to speak, explain," originally "speak in the assembly," from agora "assembly").
Also in Old English and Middle English as "to write, state or declare in writing." Of things, "be expressive or significative," by 1530s.
Speak is more general in meaning than
talk. Thus, a man may
speak by uttering a single word, whereas to
talk is to utter words consecutively ; so a man may be able to
speak without being able to
talk.
Speak is also more formal in meaning : as, to
speak before an audience ; while
talk implies a conversational manner of speaking. [Century Diuctionary]
To speak out is from late 14c. as "speak loudly;" by 1690s as "speak freely and boldly." To speak up "speak on behalf" (of another, etc.) is by 1705; as "speak loudly" by 1723. To speak for "make a speech on behalf of" is by c. 1300; to speak for itself "be self-evident" is by 1779.
Speaking terms "relationship between two in which they converse with one another" is from 1786, often in the negative. As a type of megaphone, speaking-tube is by 1825; speaking-trumpet by 1670s.