The headword is the Ionic (unaspirated) form of the aorist infinitive active of meqi/hmi ('I let go, ignore, allow to escape'; cf. mu 417, mu 425, mu 426, mu 427, Hesychius mu526) and has nothing to do with the forms of the verbs for coming and going in the glosses here (see mu 784, mu 789, mu 782).
[1] An approximation of Herodotus 1.128.2: prw=ton me\n tw=n ma/gwn tou\s o)neiropo/lous, oi(/ min a)ne/gnwsan metei=nai to\n *Ku=ron, tou/tous a)neskolo/pise ("He first impaled the Magi dream-interpreters who induced him to let Cyrus go"); cf. alpha 2216, and for Cyrus see generally kappa 2777 and kappa 2778. The entry appears to be based on a mistranslation of the headword in the sentence, which refers to Astyages' actions after some of the Magi (mu 28, cf. mu 25) had interpreted a dream and induced him to let Cyrus go (ch. 120ff.), thus opening the path for Cyrus' rebellion.