An igneous rock of any composition that contains conspicuous phenocrysts in a finegrained groundmass; a porphyritic igneous rock. The term (from a Greek word for a purple dye) was first applied to a purple-red rock quarried in Egypt and characterized by phenocrysts of alkali feldspar. The rock name descriptive of the groundmass composition usually precedes the term; e.g., diorite porphyry. Obsolete syn: porphyrite.