acre

English acre comes from Old English æcer, meaning a field where crops are grown, from Proto-West Germanic *akr, from Proto-Germanic *akraz ("field"), ultimately from Proto-Indo-European *h₂éǵros ("field").

The word began simply meaning "field" and narrowed over time into a fixed unit of land measurement, the sense it keeps today.

Acre is a doublet of agriculture, both tracing back to the same Proto-Indo-European root for "field." It's also cognate with Latin ager and Ancient Greek ἀγρός (agrós), both meaning "field," as well as German Acker and Dutch akker.