What is another name for a strikebreaker in America?

Strikebreakers are also called blacklegs. These are people who work despite an ongoing strike.

Strikebreakers are usually individuals who were not employed by the company prior to the trade union dispute, but rather hired after or during the strike to keep the organization running. "Strikebreakers" may also refer to workers (union members or not) who cross picket lines to work.

Strikebreaking is also known as "black-legging" or "blacklegging". American lexicographer Stephanie Smith suggests that the word has to do with bootblacking or shoe polish, for an early occurrence of the word was in conjunction with an 1803 American bootmaker's strike. However, in the 18th century, the word "blackleg" was also used in the sense "infectious disease of cattle and sheep".