erst·while /ˈɝstˌ(h)waɪl/
 (ad.)以前,往昔地(a.)以前的,往昔的
 Erst·while adv. Till then or now; heretofore; formerly. [Archaic]
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 erstwhile
      adj : belonging to some prior time; "erstwhile friend"; "our
            former glory"; "the once capital of the state"; "her
            quondam lover" [syn: erstwhile(a), former(a), once(a),
             onetime(a), quondam(a), sometime(a)]
      adv : at a previous time; "once he loved her"; "her erstwhile
            writing" [syn: once, formerly, at one time, erst]