不翼而飞[bù yì ér fēi ]
词典“fly without wings” -- disappear without any trace
词典take wings to itself：不翼而飞。
词典vanish all of a sudden：不翼而飞。
词典danci.911cha.com
词典disappear suddenly：不翼而飞。
不翼而飞[bù yì ér fēi]
（东西突然不见了） “fly without wings” -- disappear without any trace; take wings to itself; vanish all of a sudden; disappear suddenly