Evidently extracted from somewhere, the headword phrase resists precise translation outside its context. It consists of a denial (ou)) followed by a particle combination where dh/ strengthens an affirmative, adversative or progressive thought indicated by me/n; see Denniston, pp. 391-3.
The entry might be generated from instances in Homer and/or Plato: e.g. Homer, Iliad 8.238 (web address 1); Plato, Theaetetus 148E (web address 2).
[1] The lemma is identically glossed in the Synagoge, Photius' Lexicon (omicron662 Theodoridis), and Lexica Segueriana 322.17.