cryp·to·spo·rid·i·um \-spȯrˈidēəm\noun Etymology: New Latin, from crypt- + spor- + -idium 1.capitalized: a genus of protozoans of the order Coccidia that are parasitic in the gut of many vertebrates including humans and sometimes cause diarrhea 2.pluralcryptospo·rid·ia\-ēə\: a protozoan of the genus Cryptosporidium