gab·bro 
(găbrō)
(găbrō)n. pl. gab·bros
A usually coarse-grained igneous rock composed chiefly of pyroxene and calcic plagioclase feldspar. Also called norite.
[Italian, perhaps from Latin glaber, bald, beardless.]
gab·broic (gă-brōĭk), gabbroid′ (găbroid′) adj.