"one of the order of priests among the ancient Celts of Gaul, Britain, and Ireland," 1560s, from French druide (16c.), from Latin druis, fem. druias (plural druidae), from Gaulish Druides, from Celtic compound *dru-wid- "strong seer," from Old Celtic *derwos "true" (from PIE root *deru- "tree," especially oak) + *wid- "to know" (from PIE root *weid- "to see"). Hence, literally, perhaps, "they who know the oak" (perhaps in allusion to divination from mistletoe). Anglo-Saxon, too, used identical words to mean "tree" and "truth" (treow).
The English form comes via Latin, not immediately from Celtic. Old English had dry "magician," presumably from Old Irish drui. The Old Irish form was drui (dative and accusative druid; plural druad), yielding Modern Irish and Gaelic draoi, genitive druadh "magician, sorcerer." Not to be confused with the United Ancient Order of Druids, a secret benefit society founded in London 1781.
fem. proper name, Latin fem. diminutive of Drusus, a frequent surname in Livian gens, earlier Drausus, of uncertain etymology, perhaps a Celtic word meaning literally "strong" (compare Old Celtic *dru- "oak," also "strong;" see Druid).
late 14c., magike, "art of influencing or predicting events and producing marvels using hidden natural forces," also "supernatural art," especially the art of controlling the actions of spiritual or superhuman beings; from Old French magique "magic; magical," from Late Latin magice "sorcery, magic," from Greek magike (presumably with tekhnē "art"), fem. of magikos "magical," from magos "one of the members of the learned and priestly class," from Old Persian magush, which is possibly from PIE root *magh- "to be able, have power."
The transferred sense of "legerdemain, optical illusion, etc." is from 1811. It displaced Old English wiccecræft (see witch); also drycræft, from dry "magician," from Irish drui "priest, magician" (see Druid). Natural magic in the Middle Ages was that which did not involve the agency of personal spirits; it was considered more or less legitimate, not sinful, and involved much that would be explained scientifically as the manipulation of natural forces.
also *dreu-, Proto-Indo-European root meaning "be firm, solid, steadfast," with specialized senses "wood," "tree" and derivatives referring to objects made of wood.
It forms all or part of: betroth; Dante; dendrite; dendro-; dendrochronology; dour; Druid; drupe; dryad; dura mater; durable; durance; duration; duress; during; durum; endure; hamadryad; indurate; obdurate; perdurable; philodendron; rhododendron; shelter; tar (n.1) "viscous liquid;" tray; tree; trig (adj.) "smart, trim;" trim; troth; trough; trow; truce; true; trust; truth; tryst.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dru "tree, wood," daru "wood, log, timber;" Greek drys "oak," drymos "copse, thicket," doru "beam, shaft of a spear;" Old Church Slavonic drievo "tree, wood," Serbian drvo "tree," drva "wood," Russian drevo "tree, wood," Czech drva, Polish drwa "wood;" Lithuanian drūtas "firm," derva "pine, wood;" Welsh drud, Old Irish dron "strong," Welsh derw "true," Old Irish derb "sure," Old Irish daur, Welsh derwen "oak;" Albanian drusk "oak;" Old English treo, treow "tree," triewe "faithful, trustworthy, honest."
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."
1723, from assumed Latin plural Ovatēs, from Greek Ouateis "soothsayers, prophets," mentioned by Strabo as a third order in the Gaulish hierarchy, from Proto-Celtic *vateis, plural of *vatis, cognate with Latin vatis, Old Irish faith, Welsh ofydd. The modern word, and the artificial senses attached to it, are from the 18c. Celtic revival and appear first in Henry Rowlands.
Now an ofydd, or, as the word is sometimes rendered into English, ovate, is commonly understood to mean an Eisteddfodic graduate who is neither a bard nor a druid; but formerly it appears to have meant a man of science and letters, or perhaps more accurately a teacher of the same. [John Rhys, "Lectures on Welsh Philology," 1877]