Scab

Part of speech: noun (n.)

1. An incrustation over a sore, wound, vesicle, or pustule, formed by the drying up of the discharge from the diseased part.

2. The itch in man; also, the scurvy. [Colloq. or Obs.]

3. The mange, esp. when it appears on sheep. Chaucer.

4. A disease of potatoes producing pits in their surface, caused by a minute fungus (Tiburcinia Scabies).

5. A slight iregular protuberance which defaces the surface of a casting, caused by the breaking away of a part of the mold.

6. A mean, dirty, paltry fellow. [Low] Shak.

7. A nickname for a workman who engages for lower wages than are fixed by the trades unions; also, for one who takes the place of a workman on a strike. [Cant]

Part of speech: verb (v.)

To become covered with a scab; as, the wound scabbed over.