weid- / Indo-European roots
Examples of words with the root weid-: -oid, advice, Atharva-Veda, Ayurveda, belvedere, black-a-vised, clairvoyant, colcannon, déjà vu, eidetic, eidolon, envy, evident, guide, guise, guy, hadal, Hades, history, idea, ideo-, idocrase, idol, idyll, interview, iwis, kaleidoscope, penguin, polyhistor, previse.
▲ Derivatives include guide, wisdom, kaleidoscope, Hades, unwitting, envy, idea, history, penguin.
I. Full-grade form *weid-.
1. a. twit from Old English wītan, to reproach; b. guide, guidon from Old Provençal guidar, to guide; c. guy1 from Old French guier, to guide; d. wite from Old English wīte, fine, penalty, from Germanic derivative noun *wīti-. a-d all from Germanic *wītan, to look after, guard, ascribe to, reproach.
2. Suffixed form *weid-to-. a. wise1 from Old English wīs, wise; b. wisdom from Old English wīsdōm, learning, wisdom (-dōm, abstract suffix; see dhē-); c. wiseacre from Old High German wīzag, knowledgeable; d. (i) wise2 from Old English wīse, wīs, manner; (ii) guise from Old French guise, manner. Both
(i) and (ii) from Germanic *wīssōn-, appearance, form, manner. a-d all from Germanic *wīssaz..
3. Suffixed form *weid-es-. eidetic, eidolon, idol, idyll, -oid; idocrase, kaleidoscope from Greek eidos, form, shape.
II. Zero-grade form *wid-.
1. a. wit1 from Old English wit, witt, knowledge, intelligence; b. witenagemot from Old English wita, wise man, councilor. Both a and b from Germanic *wit-.
2. wit2, wot; unwitting from Old English witan, to know, from Germanic *witan (Old English first and third person singular wāt, from Germanic *wait, from Indo-European o-grade form *woid-).
3. Suffixed form *wid-to-. iwis from Old English gewis, gewiss, certain, sure, from Germanic *(ga)wissa-, known (*ga-, past participial prefix; see kom)
4. Form *wid-ē- (with the participial form *weid-to-) vide, view, visa, visage, vision, visit, visor, vista, voyeur; advice, advise, belvedere, black-a-vised, déjà vu, clairvoyant, envy, evident, improvise, interview, invidious, previse, provide, prudent, purvey, purview, review, revise, supervise, survey from Latin vidēre, to see, look.
5. Suffixed form *wid-es-yā-. idea, ideo- from Greek ideā, appearance, form, idea.
6. Suffixed form *wid-tor-. history, story1; polyhistor from Greek histōr, wise, learned, learned man.
7. hadal, Hades from Greek Haidēs (also Aïdēs), the underworld, perhaps "the invisible" and from *wid-.
8. Suffixed nasalized zero-grade form *wi-n-d-o-. a. colcannon from Old Irish find, white (< "clearly visible"); b. penguin from Welsh gwyn, gwynn, white.
9. Celtic *wid-, seer, in compound *dru-wid- (see deru-)
III. Suffixed o-grade form *woid-o-. Veda; Rig-Veda from Sanskrit vedaḥ, knowledge.
[Pokorny 2. u̯(e)di- (misprint for u̯(e)id-) 1125.]