Old English seems to have had the word *hægfore 'heifer.' The first element (*hæg-) presumably meant 'enclosure' (as do haw and hedge), whereas -fore was a suffix meaning 'dweller, occupant' ....In modern use a female that has not yet calved, as opposed to a cow, which has, and a calf, which is an animal of either sex not more than a year old. As derisive slang for "a woman, girl" it dates from 1835.