scab

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A crust discharged from and covering a healing wound.
• noun Scabies or mange in domestic animals or livestock, especially sheep.
• noun Any of various plant diseases caused by fungi or bacteria and resulting in crustlike spots on fruit, leaves, or roots.
• noun The spots caused by such a disease.
• noun Slang A person regarded as contemptible.
• noun A worker who refuses membership in a labor union.
• noun An employee who works while others are on strike; a strikebreaker.
• noun A person hired to replace a striking worker.
• intransitive verb To become covered with scabs or a scab.
• intransitive verb To work or take a job as a scab.

from The Century Dictionary.

• To form a scab or scabby incrustation; become covered with a scab or scabs; specifically, to heal over; cicatrize; repair solution of continuity of a surface by the formation of a new skin or cicatrix.
• noun An incrusted substance, dry and rough, formed over a sore in healing.
• noun The mange, or some mangy disease caused by the presence of a parasite, as an itch-insect; scabies.
• noun A mean, paltry, or shabby fellow: a term of contempt.
• noun Specifically, in recent use, a workman who is not or refuses to become a member of a labor-union, who refuses to join in a strike, or who takes the place of a striker: an opprobrious term used by the workmen or others who dislike his action.
• noun In botany, a fungous disease affecting various fruits, especially apples and pears, in which a black mold appears, often distorting or destroying the fruit.
• noun In founding, any projection on a casting caused by a defect in the sand-mold.
• Having to do with “scabs,” or made by them: used opprobriously: as, scab mills; scab labor; scab shoes.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb To become covered with a scab.
• intransitive verb to take the place of a striking worker.
• noun An incrustation over a sore, wound, vesicle, or pustule, formed by the drying up of the discharge from the diseased part.
• noun Colloq. or Obs. The itch in man; also, the scurvy.
• noun The mange, esp. when it appears on sheep.
• noun A disease of potatoes producing pits in their surface, caused by a minute fungus (Tiburcinia Scabies).
• noun (Founding) A slight irregular protuberance which defaces the surface of a casting, caused by the breaking away of a part of the mold.
• noun Low A mean, dirty, paltry fellow.
• noun Cant 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.
• noun (Bot.) Any one of various more or less destructive fungus diseases attacking cultivated plants, and usually forming dark-colored crustlike spots.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An incrustation over a sore, wound, vesicle, or pustule, formed during healing.
• noun The scabies.
• noun The mange, especially when it appears on sheep.
• noun Several different diseases of potatoes producing pits and other damage on their surface, caused by Streptomyces -bacteria.
• noun Short form for common scab, a relatively harmless variety of scab caused by Streptomyces scabies.
• noun botany Any one of various more or less destructive fungus diseases attacking cultivated plants, and forming dark-colored crustlike spots.
• noun founding A slight irregular protuberance which defaces the surface of a casting, caused by the breaking away of a part of the mold.
• noun A mean, dirty, paltry fellow.
• noun slang A worker who acts against trade union policies, especially a strikebreaker.
• verb intransitive To become covered by a scab or scabs.
• verb intransitive To form into scabs and be shed, as damaged or diseased skin.
• verb transitive To remove part of a surface (from).
• verb intransitive To act as a strikebreaker.
• verb transitive, Australia, New Zealand, informal To beg (for), to cadge or bum.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb take the place of work of someone on strike
• verb form a scab
• noun someone who works (or provides workers) during a strike
• noun the crustlike surface of a healing skin lesion