Univerbation of bec + d' + âne, literally “donkey's muzzle”, though it is possible that âne here originally represents Old French ane (“duck”), from Latin anas, thus “duck’s beak”. The pronunciation /be/ is the Middle French preconsonantal form of bec, later displaced by the prevocalic/pausal pronunciation /bɛk/, but preserved in idioms (cf. béjaune).