streptococcus vs streptococci

streptococcus and streptococci both are nouns.

Word	Noun	Adjective	Verb	Adverb
streptococcus	Yes	No	No	No
streptococci	Yes	No	No	No

As nouns, streptococcus and streptococci are synonyms defined as:

streptococcus and streptococci: spherical Gram-positive bacteria occurring in pairs or chains; cause e.g. scarlet fever and tonsillitis

Other synonyms of streptococcus include strep.

streptococcus (noun)	streptococci (noun)
spherical Gram-positive bacteria occurring in pairs or chains; cause e.g. scarlet fever and tonsillitis	spherical Gram-positive bacteria occurring in pairs or chains; cause e.g. scarlet fever and tonsillitis