Plica

Besides what Webster 1913 mentions, plica also apparently means a fold in skin or tissue. It could be anywhere in or on the body. Depending on where it is, it might have a specific name. For example, the fold in the floor of the mouth, under the tongue, is called the plica sublingualis. Bet you're going to use that gem of verbiage frequently from now on. Go on, I dare you.

Pli"ca (?), n. [LL., a fold, fr. L. plicare to fold. See Ply, v.]

1. Med.

A disease of the hair (Plica polonica), in which it becomes twisted and matted together. The disease is of Polish origin, and is hence called also Polish plait.

Dunglison.

2. Bot.

A diseased state in plants in which there is an excessive development of small entangled twigs, instead of ordinary branches.

3. Zool.

The bend of the wing of a bird.

© Webster 1913.