The headword -- presumably extracted from somewhere, but too commonplace to be tracked down -- is the second aorist passive infinitive of ph/gnumi (pi 1490). (The first aorist passive e)ph/xqhn occurs less frequently. See LSJ s.v.) The gloss is a later and very much rarer form; in fact, attested only here and in recensio E of the Historia Alexandri Magni (25.4).