"settle again," 1540s (transitive), in reference to places, from re- "back, again" + settle (v.). Intransitive sense of "become settled again" is from 1821. The meaning "bring into order again" is from 1610s. Related: Resettled; resettling.
"act of resettling; a fresh settlement," in any sense, 1630s, from resettle + -ment. In a South African racial context from 1954.