from Wiktionary, Creative Commons Attribution/Share-Alike License
- adv. On the day before yesterday.
- n. The day before yesterday.
From Old English ǣr. (adverb, conjunction & preposition), from Proto-Germanic *airiz comparative of Proto-Germanic *airi (“early”), from Proto-Indo-European *áyeri (“day, morning”) (compare Avestan 𐬀𐬫𐬀𐬭 (ayar, "day"), Ancient Greek ἠέριος (ēérios, "at daybreak"), see also era) + Middle English, from Old English geostran dæg, compounded from geostran ("yesterday"), from Proto-Germanic *gestra-, from Proto-Indo-European *ghes; + Middle English day, from Old English dæg, from Proto-Germanic *dagaz, from Proto-Indo-European *dhegh- (“to burn”). (Wiktionary)