pneu·mo·coc·cus 
(n′mə-kŏkəs, ny′-)
(n′mə-kŏkəs, ny′-)n. pl. pneu·mo·coc·ci (-kŏksī′, -kŏkī′)
A nonmotile, gram-positive bacterium (Streptococcus pneumoniae) that is the most common cause of bacterial pneumonia and is a cause of meningitis and other infectious diseases.
pneu′mo·coccal (-kŏkəl) adj.