so·cial·ist 
(sōshə-lĭst)
(sōshə-lĭst)n.
1. An advocate of socialism.
2. often Socialist A member of a political party or group that advocates socialism.
adj.
1. Of, promoting, or practicing socialism.
2. Socialist Of, belonging to, or constituting a socialist party or political group.
so′cial·istic adj.
so′cial·isti·cal·ly adv.