'gangster' originates from English, formed by combining 'gang' (a group or company) with the agent suffix '-ster' in the late 19th century (United States), where the compound denoted a person belonging to a gang.

'gang' comes from Old English 'gang' meaning 'a going, way, a company' (from Proto-Germanic *gangaz), and the suffix '-ster' derives from Old English '-estre' (an agent-forming suffix). These elements combined in English to form 'gangster' in the late 1800s and the term became widespread in early 20th-century American English to refer to members of criminal gangs.

Initially it simply meant 'a member of a gang,' but over time it evolved to specifically mean 'a member of an organized criminal gang' (often with connotations of violence or organized crime), especially after the Prohibition era.