"a bending or drooping," 1580s, in nautical use, "movement to leeward," from sag (v.). From 1727 in American English in reference to landforms having a sunken look. By 1861 in reference to droop from slackness in wires, cables, etc.
"to look on at a card game and offer unwelcome advice," 1915, from Yiddish kibitsen "to offer gratuitous advice as an outsider," from German kiebitzen "to look on at cards, to kibitz," originally in Rotwelsch (thieves' cant) "to visit," from Kiebitz, name of a shore bird (European peewit, lapwing) with a folk reputation as a meddler, from Middle High German gibitz "pewit," imitative of its cry (see peewit). Young lapwings are proverbially precocious and active, and were said to run around with half-shells still on their heads soon after hatching. Related: Kibitzing. Also see kibitzer.
"demonstrable proposition in science or mathematics," 1550s, from French théorème (16c.) and directly from Late Latin theorema, from Greek theorema "spectacle, sight," in Euclid "proposition to be proved," literally "that which is looked at," from theorein "to look at, behold" (see theory).
"Suspicion" words in other Indo-European languages also tend to be words for "think" or "look" with prefixes meaning "under, behind;" such as Greek hypopsia (hypo "under," opsis "sight"), hyponoia (noein "to think"); Lettish aizduomas (aiz "behind," duomat "think"); Russian podozrenie (Slavic podu "under," Old Church Slavonic zireti "see, look"); Dutch achterdocht (achter "behind," denken "to think").
"wonder-worker," 1715, from Medieval Latin thaumaturgus, from Greek thaumatourgos "wonder-working; conjurer," from thauma (genitive thaumatos) "wonder, astonishment; wondrous thing," literally "a thing to look at," from root of theater, + -ourgia "a working," from ergon "work" (from PIE root *werg- "to do").
[instrument for viewing] 1872, shortened from telescope, microscope, etc., in which the element (Latinized) is from Greek skopein "to look" (from PIE root *spek- "to observe"). Earlier used as a shortening of horoscope (c. 1600). Extended to radar screens, etc., by 1945 as a shortening of oscilloscope.