nucellus
noun
nu·cel·lus nü-ˈse-ləs 
nyü-
plural nucelli nü-ˈse-ˌlī
nyü-
: the central and chief part of a plant ovule that encloses the female gametophyte
nucellar
nü-ˈse-lər
adjective nyü-
Word History
Etymology
New Latin, from Latin nucella small nut, from nuc-, nux nut — more at nut
First Known Use
1882, in the meaning defined above