Entry 2 senses · 2 variants Webster, 1913 Opercular · O·per·cu·lar · IPA a. n. 01 a. Of, pertaining to, or like, an operculum. 1. Of, pertaining to, or like, an operculum. 02 n. The principal opercular bone or operculum of fishes. 1. The principal opercular bone or operculum of fishes.(Anat.)