- a shrewd, practical person.
- a blockhead.
- a freshwater fish, Mylopharodon conocephalus, of California.
- the Atlantic croaker.See under croaker(def 2).
- hardhead sponge.
- hardheads. a common knapweed, Centaurea nigra.
- hard head.
- an alloyed silver coin of Scotland, issued in the 16th and 17th centuries, equal to one and one-half pence and later to twopence.
- any composite plant of the genus Centaurea, especially the weedy C. nigra, having rose-purple flowers set on a dark-colored, knoblike bract.
- (functioning as singular) a thistle-like plant, Centaurea nigra, native to Europe and introduced into North America and New Zealand, that has reddish-purple flower heads: family Asteraceae (composites)Also called: knapweed See also centaury (def. 2)