One who caves or gives in too easily. Doesn't put up a stand/ a fight for what they want to do or believe is true. Surrenders to the will of someone else.
Martin is such a caver. He wanted to go see this other band really bad but we didn't so he caved and came with us.
White people travel to developing countries in search of young children to rescue from "caves". Choice destinations include Thailand, the Philippines, Cambodia, the Gambia, Kenya, etc
(noun): one who can often be characterized as giving in to the will of others, though never used pejoratively as these persons are likely to be badass lady friends :o