didinium
noun
di·din·i·um
dīˈdinēəm
1
capitalized : a genus of carnivorous protozoans (order Holotricha) that feed on paramecia
2
plural didiniums
-mz
or didinia -nēə
: any protozoan of the genus Didinium 
Word History
Etymology
New Latin, from di- + Greek deinos terrible + New Latin -ium