1763 as an insect genus (including the cochineal bug); 1883 as a type of bacterium, from Greek kokkos "grain, seed, berry" (see cocco-).
coccus coc·cus (kŏk'əs)n. pl. coc·ci (kŏk'sī, kŏk'ī) A bacterium of round, spheroidal, or ovoid form.
-coccus suff. A microorganism of spherical or spheroidal shape: streptococcus.