'breastfeed' originates from Modern English, a compound of 'breast' + 'feed', where 'breast' ultimately comes from Old English 'brēost' meaning 'breast' and 'feed' comes from Old English 'fēdan' meaning 'to nourish'.

'breast' derived from Old English 'brēost' and 'feed' from Old English 'fēdan'; the compound 'breastfeed' developed in Modern English to denote feeding at the breast.

Initially it meant 'to feed at the breast' and this core meaning has largely remained, though usage has extended to include expressing milk and the noun sense 'a feeding session'.