Etymology
1. From Middle English even, from Old English efn (“flat; level, even, equal”), from Proto-West Germanic *ebn, from Proto-Germanic *ebnaz, from Proto-Indo-European *(h₁)em-no- (“equal, straight; flat, level, even”).
2. Cognate with Saterland Frisian íeuwen (“even, flat”), West Frisian even (“even”), Alemannic German ëben (“even”), Cimbrian ébane (“even”), Dutch even (“even, equal, same”), effen (“leveled”), German eben (“even, flat, level”), Danish jævn (“even, flat, smooth”), Icelandic jafn (“even”), Norwegian Bokmål jevn (“even, smooth”), Norwegian Nynorsk jamn (“even, smooth”), Swedish jämn (“even, level, smooth”), Gothic 𐌹𐌱𐌽𐍃 (ibns, “even”), Old Cornish eun (“equal, right”) (attested in Vocabularium Cornicum eun-hinsic (“iustus, i. e., just”)), Old Breton eun (“equal, right”) (attested in Eutychius Glossary eunt (“aequus, i. e., equal”)), Middle Breton effn, Breton eeun, Sanskrit अम्नस् (amnás, “(adverb) just, just now; at once”).
3. The verb descends from Middle English evenen, from Old English efnan; the adverb from Middle English evene, from Old English efne.
4. The traditional proposal connecting the Germanic adjective with the root Proto-Indo-European *h₂eym- (Latin imāgō (“picture, image, likeness, copy”), Latin aemulus (“competitor, rival”), Sanskrit यम (yamá, “pair, twin”)) is problematic from a phonological point of view.
5. For the meaning development compare with Latin aequus (“equal, level, even, flat, horizontal”), Russian ро́вный (róvnyj, “even, level, flat, smooth”), ра́вный (rávnyj, “equal”), по́ровну (pórovnu, “in equal parts”). See: Dutch '
even', German, old spelling '
eben', Middle Breton 'effn', Old English '
efnan'.