Definition of costard in English:

costard

(also costard)

noun

British
  • 1A cooking apple of a large ribbed variety.

    • ‘The cooking equivalent was the Costard, which gave rise to the term costermonger, first applied to apple salesmen.’
    1. 1.1archaic, humorous A person's head.

Origin

Middle English: from Anglo-Norman French, from coste rib from Latin costa.

Pronunciation:

costard

/ˈkästərd/