left wing

Short definition from Wiktionary

Noun

1. 1
   The wing on the left side of some body, most commonly one half of a pair
2. 2
   The wing on the left side of some body, most commonly one half of a pair: The more left-wing faction of a group, party, or group of parties.
3. 3
   The wing on the left side of some body, most commonly one half of a pair: The left-hand side of a sports field.
4. 4
   The wing on the left side of some body, most commonly one half of a pair: The offensive player who plays to the center's left.

Adjective

1. 1
   Of political ideologies: favoring political, social, and economic equality.