Definition of hardyhead in US English:

hardyhead

(also hardihead)

noun

Australian
  • Any of various small silvery fishes of the family Atherinidae; especially the marine fish Atherinomorus lacunosus of the Indo-Pacific, and freshwater fishes of the genus Craterocephalus, which are endemic to Australia and New Guinea.

Origin

Late 19th century; earliest use found in Proceedings of the Linnean Society of New South Wales. Probably from hardy + head.

Pronunciation

hardyhead

/ˈhɑːdɪhɛd/