The headword is perfect middle/passive participle of the verb xrhsmw|de/w (see under chi 503) in the masculine or neuter genitive plural. Same entry in Photius, Lexicon kappa644 Theodoridis; similar one in the Synagoge and elsewhere, including Hesychius kappa2435 (neuter nominative plurals).
The genitive plural participle glossed here is first attested in Cyril of Alexandria (4 times: Commentary on the Twelve Minor Prophets I p. 346 Pusey, Dialogues On the Holy Trinity p. 397 Aubert, PG 68.725, 68.781, 69.568). However, the locus classicus for the participle is Plato, Letters 323C, in the neuter plural nominative, matching the headword in Hesychius (above). The later lexicographers' genitive might be a corruption of Hesychius' entry.