9 letters · 15 points in Scrabble
noun a hard flap serving as a cover for (a) the gill slits in fishes or (b) the opening of the shell in certain gastropods when the body is retracted
originEtymology tree Proto-Indo-European *h₁ep-der. Proto-Indo-European *h₁épsder. Proto-Indo-European *h₁epi Proto-Indo-European *h₂wer- Proto-Indo-European *-yeti Latin operiō Latin -culum Latin operculumbor. English operculum Borrowed from Latin operculum.
Etymology from Wiktionary, CC BY-SA 3.0