The Collaborative International Dictionary of English v.0.48:

Opercular \O*per"cu*lar\, a.
   Of, pertaining to, or like, an operculum.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Opercular \O*per"cu*lar\, n. (Anat.)
   The principal opercular bone or operculum of fishes.
   [1913 Webster] Operculate