An Etymological Dictionary of the German Language/Annotated/Jahr
Jahr, neuter, ‘year,’ from the equivalent Middle High German and Old High German jâr, neuter; a common Teutonic term; compare Gothic jêr, Old Icelandic ár, Anglo-Saxon geâr, English year, Dutch jaar, Old Saxon jâr (gêr), neuter, ‘year.’ The original meaning of the word, which also appears in heuer, seems to be ‘spring,’ as is indicated by the Slavonic cognate jarŭ, ‘spring’; compare also Greek ὥρα, ‘season, spring, year,’ and ὥρος, ‘year,’ so too Zend yâre, ‘year’; in Indian a similar term is wanting (compare Sommer and Winter). For the change of meaning see the history of the word Winter.