enterococcus UK /ˌɛntəɹə(ʊ)ˈkɒkəs/US /ˌɛntəɹoʊˈkɑkəs/ noun1 •Any of a group of streptococci bacteria, of the genus Enterococcus, that inhabit the human gastrointestinal tract and have great resistance to antibiotics formsenterococci