Definition of conehead:
(n) :
(sports, fandom slang, slang) A fan of baseball pitcher David Cone.
(n) :
(fiction) One of a fictional race of humanoid aliens with conical skulls.
(n) :
(slang) A pinhead, a stupid person.
(n) :
(fashion) A foam rubber rounded cone hat to be worn atop the head as a costume to appear to have a conical bald skull.
(n) :
(Australia, slang) A person addicted to smoking marijuana with a bong.
(n) :
(anthropology, archaeology, informal) A person who has undergone cranial modification in order to produce an elongated skull.