Emily Dickinson Lexicon

BAR'NA-CLE, n. [Port. bernaca, the Solan goose; Fr. barnacle, or barnaque; L. perna, a shell-fish.]

1. A shell which is often found on the bottoms of ships, rocks, and timber, below the surface of the sea.
2. A species of goose, found in the northern seas, but visiting more southern climates in winter. The forehead and cheeks are white, but the upper part of the body and neck is black. Formerly, a strange notion prevailed, that these birds grew out of wood, or rather out of the barnacles attached to wood in the sea. Hence the name. It is written also Bernacle. – Pennant.
3. In the plural, an instrument consisting of two branches joined at one end with a hinge, to put upon a horse's nose, to confine him, for shoeing, bleeding, or dressing. – Encyc.