Costard /(k?s"t?rd)/

Cos·tard

Costard

n.
  1. An apple, large and round like the head.
    Some [apples] consist more of air than water . . . ; others more of water than wind, as your costards and pomewaters.
    — Muffett.
  2. The head; -- used contemptuously.
    Try whether your costard or my bat be the harder.