peridinium
noun
peri·din·i·um
ˌperəˈdinēəm
1
capitalized : the type genus of Peridiniidae comprising marine and freshwater dinoflagellates that are typically subspherical to ovoid in outline and that sometimes have the test prolonged into short horns compare ceratium
2
plural peridiniums
-ēəmz
or peridinia -ēə
: any flagellate of the genus Peridinium 
Word History
Etymology
borrowed from New Latin, borrowed from Greek peridīn-, base of peridīneîn "to whirl, spin around" (from peri- peri- + dīneîn "to whirl, spin about") + New Latin -ium -ium
- cresswort
- cressy
- crest
- crest clearance
- crest coronet
- crest fern
- crest line
- crest rail
- crest table
- crest tile
- crest voltmeter
- crestal
- crested
- crested auk
- crested auklet
- crested barbet
- crested cariama
- crested coralroot
- crested dogstail
- crested duck
- crested dwarf iris
- crested fern
- crested flycatcher
- crested guinea fowl
- crested hair grass