n. a genus of spherical Gram-negative aerobic nonmotile bacteria characteristically grouped in pairs. They are parasites of animals, and some species are normal inhabitants of the human respiratory tract. The species N. gonorrhoeae (the gonococcus) causes *gonorrhoea. Gonococci are found within pus cells of urethral and vaginal discharge; they can be cultured only on serum or blood agar. N. meningitidis (the meningococcus) causes meningococcal *meningitis. Meningococci are found within pus cells of infected cerebrospinal fluid and blood or in the nasal passages of carriers. They too can only be cultured on serum or blood agar.