1. An infectious, usually fatal bacterial disease of cattle and sometimes of sheep, goats, and swine, caused by Clostridium chauvoei and characterized by gas-containing swellings in the musculature.

2. A bacterial or fungal disease of certain plants, such as the cabbage and potato, that causes the stems to turn black at the soil line.

3. One who cheats at cards; a cardsharp.

4. Chiefly British A worker who is opposed to trade unions; a scab.