used (adj.) Look up used at Dictionary.com
"second-hand," 1590s, past participle adjective from use (v.). To be used to "accustomed, familiar" is recorded by late 14c. Verbal phrase used to "formerly did or was" (as in I used to love her) represents a construction attested from c.1300, and common from c.1400, from use (intransitive) "be accustomed, practice customarily," but now surviving only in past tense form. The pronunciation is affected by the t- of to. Used-to-be (n.) "one who has outlived his fame" is from 1853.