— opercular , adj.
/oh perr"kyeuh leuhm/ , n. , pl. opercula /-leuh/ , operculums .
1. Bot. , Zool. a part or organ serving as a lid or cover, as a covering flap on a seed vessel.
2. Zool.
a. the gill cover of fishes and amphibians. See diag. under fish .
b. (in many gastropods) a horny plate that closes the opening of the shell when the animal is retracted.
[ 1705-15; oper ( ire ) to cover + -culum -CULE 2 ]