—n. 1. the incrustation that forms over a sore or wound during healing.
2. Vet. Pathol.a mangy disease in animals, esp. sheep; scabies. Cf. itch (def. 10).
3. Plant Pathol. a. a disease of plants characterized by crustlike lesions on the affected parts and caused by a fungus or bacterium.
b. one of these crustlike lesions.
4. a worker who refuses to join a labor union or to participate in a union strike, who takes a striking worker's place on the job, or the like.
5. Slang.a rascal or scoundrel.
6. Metall. a. a projection or roughness on an ingot or casting from a defective mold.
b. a surface defect on an iron or steel piece resulting from the rolling in of scale.
7. Carpentry.a short, flat piece of wood used for various purposes, as binding two timbers butted together or strengthening a timber at a weak spot.
—v.i. 1. to become covered with a scab.
2. to act or work as a scab.