Webster's Revised Unabridged Dictionary · 1913

left-wing

left-wing , adjective

1.
Of or pertaining to the political left or its ideology.
2.
Believing in or supporting tenets of the political left.

left wing , noun

Those trying to reform the established order, particularly in political matters, to enhance the condition of the common people; -- sometimes applied to those advocating overthrow of an existing government by radical means.