1. (noun) hāpuku, groper, grouper, Polyprion oxygeneios - a large heavy-bodied fish with a big head and wide mouth found in warm seas. The head is pointed and has a protruding lower jaw. Blue-grey to brown on back, changing abruptly midbody to dirty white, lightening to pale white ventrally. Circumglobal in subtropical and temperate seas of the Southern Hemisphere.