yellowhead noun7 •(informal) A pimple or pustule without a blackhead.A pustule is the typical pus spot or yellowhead. — 2007 •A mohua (Mohoua ochrocephala), a bird of New Zealand. •A plant of some species of genus Inula of the daisy family. •A yellowhead butterflyfish (Chaetodon xanthocephalus). •A yellowheaded jawfish (Opistognathus aurifrons). •A plant of species Zanthoxylum flavum, related to citrus. •A plant in genus Trichoptilium, in the daisy family. formsyellowheads