coccidia Syllabification: (coc·cid·i·a)Pronunciation: /käkˈsidēə/Definition of coccidia noun (singular coccidium /-ˈsidēəm/) Biology parasitic protozoa of a group that includes those that cause diseases such as coccidiosis and toxoplasmosis. Suborder Eimeriorina (formerly order or subclass Coccidia), phylum Sporozoa Derivatives coccidian adjective & noun coccidia in other Oxford dictionaries Definition of coccidia in the British & World English dictionary