before the 12th century, in the meaning defined at sense 1a
Middle English ook, oke, going back to Old English āc, going back to Germanic *eik- (whence also Old Frisian ēk "oak," Old Saxon ēc, Old High German eih, eihha, Old Norse eik), of obscure origin
Note: Old English āc is a feminine root noun (dative singular and nominative plural ǣc), though forms leveled to other declensions with umlaut are already evident. Germanic *eik- has been compared with the Greek words aigílōps, a name in Theophrastus for a species of oak (Quercus macrolepis?), and krátaigos, a species of hawthorn (also in Theophrastus), but interpretation of the conjoined elements of these words is conjectural (lṓpē is not actually attested in the sense "cork" or "bark"). The derivation of Latin aesculus "a species of oak (Quercus petraea?)" is obscure. The Lithuanian dialect forms áižuols and áužuolas "oak," superficially comparable, are hypercorrections of ą́žuolas, which is very unlikely to be related to *eik- (cf. Old Prussian ansonis = German eche in the Elbing Vocabulary).
oak
nounoak
noun