Headword and gloss are present participles in the masculine nominative plural, the headword one from the verb e)gkaqei/rgnumi.
Same entry, according to Adler, in the Ambrosian Lexicon (107); also, as corrected, in Hesychius epsilon180. The headword is perhaps extracted from the Commentary on Isaiah of Cyril of Alexandria (PG 70.209.41), its only independent attestation.
The headword verb, e)gkaqei/rgw, is common in the Byzantine period; rarer earlier but some instances in e.g. Josephus and Plutarch; see LSJ s.v.