Wordnet 3.0
ADJECTIVE (1)
1. 
 tending toward the political left; 
The Collaborative International Dictionary of English v.0.48:
leftish \leftish\ adj.
   Inclined toward the political left.
   [WordNet 1.5]
WordNet (r) 3.0 (2006):
leftish
    adj 1: tending toward the political left