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 Any of several different diseases of potatoes producing pits and other damage on their surface, caused by streptomyces bacteria (but formerly believed to be caused by a fungus).
noun Common scab, a relatively harmless variety of scab (potato disease) caused by Streptomyces scabies.
noun Any one of various more or less destructive fungal diseases that attack cultivated plants, forming dark-colored crustlike spots.
noun A slight irregular protuberance which defaces the surface of a casting, caused by the breaking away of a part of the mold.