Definition of "bullhead"

(Canada, US) any of a variety of related species of generally dark-colored catfish in the family Ictaluridae.

1. (Canada, US) The black bullhead, Ameiurus melas.  examples

2. (Canada, US) The brown bullhead, Ameiurus nebulosus.  examples

3. (Canada, US) The yellow bullhead, Ameiurus natalis.  examples

(Europe, Asia) Any of various sculpins of the suborder Scorpaenoidei  examples

(Europe, Asia) The European bullhead, Cottus gobio.  examples

(New Zealand) A fish of species Gobiomorphus gobioides.  examples

A bullhead shark (Heterodontus spp.).  examples

(rare) An obstinate person.

(rail transport) A bullhead rail.  examples

(horology) A chronograph (watch or stopwatch) with two push buttons arranged like the horns of a bull on the top end of the case, typically with the crown between them.