COSTARD
Etymology
Noun
costard (plural costards)
(British) A large cooking apple.
The tree on which large cooking apples grow.
(archaic, humorous) The human head.
Source: Wiktionary
Cos"tard (ks"trd), n. Etym: [Prob. fr. OF. coste rib, side, F. cΓ΄te,
and meaning orig., a ribbed apple, from the ribs or angles on its
sides. See Coast.]
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. Shak.
Source: Webster’s Unabridged Dictionary 1913 Edition