Blackleg

Blackleg has become a derogatory term for a strike breaker i.e. a worker willing to work for an employer whose other workers are on strike and this usage dates from the mid-18th century. The origin is far from certain although there are many theories. Because the first citation for its current meaning was in The New Scotsman in 1844, it may have Scottish origins, but before it took on this meaning, blackleg, during the 1700s, used to be a term for a cheat, swindler or scoundrel. Some sources maintain that this meaning is derived from the bird, the rook, which is known for its thievish propensities and, like most corvids (crows, ravens etc); it has black legs and feet. The link between this earlier meaning and scoundrels who continue to work for an employer, whose other workers are on strike, seems plausible. Folk etymologies of blacklegs being strike-breaking coalminers, with legs black from coal dust, are definitely not the origin. See also Rook.