noun Download 🔗Share A spherical, gram-positive bacterium of the genus Streptococcus. Although commonly found benignly in the human mouth and gut, and though many species are non-pathogenic, other species can cause diseases including strep throat and more serious conditions. Examples : "My doctor suspects I have strep throat because the culture came back positive for Streptococcus. " medicine biology organism microorganism disease science Chat with AIVocabulary GamePractice Reading