In most mss and as printed by Adler, this is the masculine accusative singular or neuter nominative/accusative singular of an adjective attested only here (composed from u(po/ and parh/i+on, the Homeric form of the word which would be parei=on). She notes, however, that ms G has u(popa/rkon, which Bernhardy wanted to emend to u(po/perkon, '(?)darkening'.