altruistic

adjective [原级]利他主义的，无私的

Couch surfers tend to see themselves as part of a tribe; unlike two people hooking up at a bar, they meet under an altruistic premise.
沙发冲浪者视自己为一个部落的成员；不像在酒吧里面邂逅的两个人，他们是在利他主义的前提下相遇。