'left-winger' originates from English, specifically formed from the compound 'left wing' plus the agent-forming suffix '-er', where 'left' referred to the left side and 'wing' referred to a side or faction.

'left-wing' developed as a political term in the late 18th century from seating arrangements in the French Revolutionary assemblies (those who sat on the left were generally more radical). The English terms 'left wing' and then 'left-winger' evolved from that usage.

Initially it meant someone who sat on the left side of an assembly; over time it came to mean a person who supports leftist or progressive political positions, and 'left-winger' came to denote an adherent or supporter of those views.