'trade-unionism' originates from modern English, formed by combining 'trade union' (itself from 'trade' + 'union') with the suffix '-ism' (from Greek '-ismos' via Latin and Old French); 'trade' referred to commerce or occupation and 'union' meant a coming together or unity.

'trade-unionism' developed in the 19th century as the phrase 'trade union' (19th century English, from Old French 'union' < Latin 'unio' from 'unus' meaning 'one') came into use to describe workers' organizations; the suffix '-ism' (from Greek '-ismos') was added to form a term for the movement or ideology.

Initially, the term primarily described the formation and existence of trade unions; over time it came to denote the broader ideology, practices, and political influence associated with unions.