sunset (n.)youdaoicibaDictYouDict
late 14c., from sun (n.) + set (v.). Perhaps from a Middle English subjunctive such as before the sun set. Old English had sunnansetlgong "sunset," while sunset meant "west." Figurative use from c. 1600. To ride off into the sunset (1963) is from the stereotypical ending of cowboy movies.
unsettle (v.)youdaoicibaDictYouDict
1590s, "undo from a fixed position," from un- (2) "reverse, opposite of" + settle (v.). Of the mind, feelings, etc., attested from 1640s. Related: Unsettled; unsettling.
unsettled (adj.)youdaoicibaDictYouDict
1590s, "not peaceful, not firmly established," from unsettle (v.) or else from un- (1) "not" + past participle of settle (v.). Meaning "not occupied by settlers" is attested from 1724.