eidolon (n.)

word-forming element meaning "like, like that of, thing like a ______," from Latinized form of Greek -oeidēs (three syllables), from eidos "form," related to idein "to see," eidenai "to know;" literally "to see" (from PIE *weid-es-, from root *weid- "to see"). The -o- is connective or a stem vowel from the previous element. Often implying an incomplete or imperfect resemblance to the thing indicated.

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

It forms all or part of: advice; advise; belvedere; clairvoyant; deja vu; Druid; eidetic; eidolon; envy; evident; guide; guidon; guise; guy (n.1) "small rope, chain, wire;" Gwendolyn; Hades; history; idea; ideo-; idol; idyll; improvisation; improvise; interview; invidious; kaleidoscope; -oid; penguin; polyhistor; prevision; provide; providence; prudent; purvey; purview; review; revise; Rig Veda; story (n.1) "connected account or narration of some happening;" supervise; survey; twit; unwitting; Veda; vide; view; visa; visage; vision; visit; visor; vista; voyeur; wise (adj.) "learned, sagacious, cunning;" wise (n.) "way of proceeding, manner;" wisdom; wiseacre; wit (n.) "mental capacity;" wit (v.) "to know;" witenagemot; witting; wot.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit veda "I know;" Avestan vaeda "I know;" Greek oida, Doric woida "I know," idein "to see;" Old Irish fis "vision," find "white," i.e. "clearly seen," fiuss "knowledge;" Welsh gwyn, Gaulish vindos, Breton gwenn "white;" Gothic, Old Swedish, Old English witan "to know;" Gothic weitan "to see;" English wise, German wissen "to know;" Lithuanian vysti "to see;" Bulgarian vidya "I see;" Polish widzieć "to see," wiedzieć "to know;" Russian videt' "to see," vest' "news," Old Russian vedat' "to know."