The Collaborative International Dictionary of English v.0.48:

Dolerite \Dol"er*ite\, n. [Gr. dolero`s deceptive, because it
   was easily confounded with diorite.] (Petrography)
   (a) A dark, crystalline, igneous rock, chiefly pyroxene with
       labradorite.
   (b) Coarse-grained basalt.
   (c) Diabase.
   (d) Any dark, igneous rock composed chiefly of silicates of
       iron and magnesium with some feldspar. -- Dol`er*it"ic,
       a.
       [Webster 1913 Suppl.]