"come to rest," Old English setlan "cause to sit, place, put," from setl "a seat" (see settle (n.)). Related: Settling. Cf. German siedeln "to settle, colonize."
From c.1300 of birds, etc., "to alight." From early 14c. as "sink down, descend; cave in." Early 15c. in reference to suspended particles in a liquid. Sense of "establish a permanent residence" first recorded 1620s; that of "decide" is 1620s. Meaning "secure title to by deed" is from 1660s.
Meaning "reconcile" (a quarrel, differences, etc.) perhaps is influenced by Middle English sahtlen "to reconcile," from Old English saht "reconciliation," from Old Norse satt "reconciliation." To settle down "become content" is from 1853; transitive sense from 1520s; as what married couples do in establishing domesticity, from 1718. To settle for "content oneself with" is from 1943.
