One full circuit of the earth around the sun, used to count a life. The unit a human span is measured in.
Old English gēar (year), from Proto-Germanic *jērą, ultimately from a Proto-Indo-European root for a season or a turning of the sun — the same distant root that underlies Greek hōra (season, hour, the source of English "hour") and Avestan yāre. The word named the sun's own circuit before it named the measure of a life lived inside it.
A length borrowed from the sky — one loop the earth makes around the sun — and turned into the unit a human span gets counted in. The measure comes from outside a life and is applied to it anyway.