ocellus
noun
ocel·lus ō-ˈse-ləs 
plural ocelli ō-ˈse-ˌlī -(ˌ)lē
-(ˌ)lē 1
: a minute simple eye or eyespot of an invertebrate
2
: an eyelike colored spot (as on a peacock feather or the wings of some butterflies)
ocellar
ō-ˈse-lər
adjective 
Word History
Etymology
New Latin, from Latin, diminutive of oculus eye — more at eye
First Known Use
1819, in the meaning defined at sense 1
Medical Definition
ocellus
noun
ocel·lus ō-ˈsel-əs
plural ocelli -ˈsel-ˌī -(ˌ)ē
-(ˌ)ē : a minute simple eye or eyespot of an invertebrate