by 1794, American English, as a shortening of speculation. By 1926 in circus slang as a shortening of spectacle. By 1956 as "detailed description or standard," especially in manufacturing and construction, short for specification. Related: Specs.

1570s, "semi-transparent" (in specular stone); 1660s, "reflective" (like a mirror), from Latin specularis, from speculum "a mirror" (see speculum).

The meaning "assisting in vision; affording a view" is from 1650s, from Latin speculari "to spy" (see speculation). Related: Specularly.

1590s, "view mentally, contemplate" (transitive), back-formation from speculation. Also formerly "view as from a watchtower" (1610s). The intransitive sense of "pursue truth by conjecture or thinking" is from 1670s. The meaning "invest money upon risk for the sake of profit" is from 1785. Related: Speculated; speculating.

Speculable as "subject to speculation, theoretical" is from mid-15c., from Latin speculabilis. Caxton had specule (v.) "regard attentively," from French speculer, but English did not keep it.

late 14c., speculatif, "theoretical, purely scientific, in theory only" (opposed to practical), from Old French speculatif "worth great attention; theoretical," or directly from Late Latin speculativus, from speculat-, past-participle stem of speculari (see speculation).

The sense of "contemplative" is attested by late 15c. The meaning "engaged in or involving (financial) speculation" is from 1763. Related: Speculatively.

1550s, "one who engages in mental speculation," from Latin speculator "a looker-out, spy, scout, explorer; investigator, examiner," agent noun from speculari (see speculation). The financial sense is from 1778. Formerly also "observer, onlooker," especially "an occult seer" (1650s), senses now obsolete. The fem. form speculatrix attested from 1610s. Related: Speculatory; speculatorial.

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."