Origin and history of espy

mid-13c., spien, "to watch stealthily," from Old French espiier "observe, watch closely, spy on, find out," probably from Frankish *spehon or some other Germanic source, from Proto-Germanic *spehon- (source also of Old High German *spehon "to look out for, scout, spy," German spähen "to spy," Middle Dutch spien). These are the Germanic survivals of the productive PIE root *spek- "to observe."

Old English had spyrian "make a track, go, pursue; ask about, investigate," also a noun spyrigend "investigator, inquirer." Italian spiare, Spanish espiar also are Germanic loan-words.

The meaning "catch sight of, discover at a distance or from a place of concealment" is from c. 1300. The intransitive meaning "play the spy, conduct surveillance" is from mid-15c. The children's game I spy was so called by 1946.

the later Romans evidently found words beginning in sc-, sp-, st- difficult or unpleasant to pronounce; in Late Latin forms begin to emerge in i- (such as ispatium, ispiritu), and from 5c. this shifted to e-. The development was carried into the Romanic languages, especially Old French, and the French words were modified further after 15c. by natural loss of -s- (the suppression being marked by an acute accent on the e-), while in other cases the word was formally corrected back to the Latin spelling (for example spécial). Hence French état for Old French estat for Latin status, etc. It also affected Romanic borrowings from Germanic (such as espy, eschew).

A different e- is a reduced form of Latin ex- before consonants (see ex-), and the e- in enough is an unfelt survival of an Old English alternative form of ge-.

Proto-Indo-European root meaning "to observe."

It might form all or part of: aspect; auspex; auspices; auspicious; bishop; circumspect; conspicuous; despicable; despise; episcopal; especial; espionage; espy; expect; frontispiece; gyroscope; haruspex; horoscope; inspect; inspection; inspector; introspect; introspection; perspective; perspicacious; perspicacity; prospect; prospective; respect; respite; retrospect; scope; -scope; scopophilia; -scopy; skeptic; species; specimen; specious; spectacle; spectacular; spectrum; speculate; speculation; speculum; spice; spy; suspect; suspicion; suspicious; telescope.

It might also be the source of: Sanskrit spasati "sees;" Avestan spasyeiti "spies;" Greek skopein "behold, look, consider," skeptesthai "to look at," skopos "watcher, one who watches;" Latin specere "to look at;" Old High German spehhon "to spy," German spähen "to spy."