What is the meaning of Blackleg?

A fatal cattle disease caused by the soil-borne bacterium Clostridium chauvoei; symptomatic anthrax.

A disease of potato crops caused by pectolytic bacteria, characterized by blackening and decay of the lower stem portion.

A person who cheats in a game; a cheater, especially a dishonest bookmaker.

A person who takes the place of striking workers; a scab.

To continue working whilst fellow workers strike.

Source: wiktionary.org