The Collaborative International Dictionary of English v.0.48:

Streptococcus \Strep`to*coc"cus\, n.; pl. Streptococci. [NL.,
   fr. Gr. ? pliant, curved + ? a grain, seed.] (Biol.)
   A long or short chain of micrococci, more or less curved.
   [1913 Webster]
   [1913 Webster]
   [1913 Webster]

WordNet (r) 3.0 (2006):

streptococcus
    n 1: spherical Gram-positive bacteria occurring in pairs or
         chains; cause e.g. scarlet fever and tonsillitis [syn:
         streptococcus, streptococci, strep]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "streptococcus":
   adenovirus, aerobe, aerobic bacteria, amoeba, anaerobe,
   anaerobic bacteria, bacillus, bacteria, bacterium, bug, coccus,
   disease-producing microorganism, echovirus, enterovirus,
   filterable virus, fungus, germ, gram-negative bacteria,
   gram-positive bacteria, microbe, microorganism, mold,
   nonfilterable virus, pathogen, picornavirus, protozoa, protozoon,
   reovirus, rhinovirus, rickettsia, spirillum, spirochete, spore,
   staphylococcus, trypanosome, vibrio, virus