operculum

n., pl., -la (-lə), or -lums.
A lid or flap covering an aperture, such as the gill cover in some fishes or the horny shell cover in snails or other mollusks.

[Latin, lid, from operīre, to cover.]

opercular o·per'cu·lar (-lər) adj.
opercularly o·per'cu·lar·ly adv.

(ōpur′kyōōləm)
n

Flap of tissue over a partially erupted tooth, particularly a third molar in periocoronitis. See also perioronitis.

Pl. opercula [L.]
1. a lid or covering.
2. the folds of pallium from the frontal, parietal and temporal lobes of the cerebrum overlying the insula.
3. gill cover in a fish.

• dental o. — the hood of gingival tissue overlying the crown of an erupting tooth.
• trophoblastic o. — the plug of trophoblast that helps close the gap in the endometrium made by the implanting blastocyst.

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