a thin plate, scale, membrane, or layer, as of bone, tissue, or cell walls.

Botany .

an erect scale or blade inserted at the junction of the claw and limb in some corollas and forming a part of their corona or crown.

(in mosses) a thin sheet of cells standing up along the midrib of a leaf.

Mycology . gill 1 ( def. 2 ) .

Building Trades . a member of wood, metal, or reinforced concrete, joined in a crisscross pattern with other lamellae to form a vault.

Ophthalmology . a small disk of gelatin and glycerin mixed with a medicinal substance, used as a medicament for the eyes.