The headword (which must be quoted from somewhere but is attested only here and, according to Adler, in the Ambrosian Lexicon) is the Ionic/koine perfect active participle, masculine nominative plural, of h(ssa/w, which usually occurs only in the middle/passive; the gloss is the Attic aorist active participle of the same verb.
Compare Diodorus Siculus 15.87.3, which has the Attic version of the headword, h(tthko/tes (web address 1).
cf. generally eta 578 and the other cross-references there.