The headword is the superlative, neuter nominative/accusative plural, of the adjective h(du/s 'pleasant' (see eta 91 and eta 92), glossed here in its adverbial sense.
Although literally taken from the Synagoge (Lexica Segueriana eta249, Bachmann), this is an entry which is similarly glossed in several different lexicographic sources: Photius, the Lexicon Ambrosianum, the Glossarium Cyrilli, and Hesychius eta126 (probably interpolated by Cyril).