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Webster 1913 Edition

(bụl′hĕdˊĕd)

Adj.

Having a head like that of a bull. Fig.: Headstrong; obstinate; dogged.

See also: bull-headed and bull headed

bullheaded ‎(comparative more bullheaded, superlative most bullheaded)

unreasonably stubborn.
John was so bullheaded that he kept driving and refused to stop for directions, even after getting hopelessly lost.