The second vowel can be either omicron, as here, or omega.
[1] Described by Photius, Lexicon lambda201.1, as “a kind of cup, wide in its structure, and having big ‘ears’ (sc. handles).” He names Menander but does not cite a passage. TLG shows fr. 24.1 and 503.1, neither of which gives any indication of the form of the object, though in each case it occurs in a list of drinking vessels. One imagines something like a phiale (phi 283, phi 284) but with handles.
[2] In fact the term appears not only in the neuter gender, as in the present headword, and in the masculine, as in the present gloss, but is also listed in the feminine: Eustathius 1066.3, λαβρώνια . The closest parallel passage is Theognostus, Canones sive de orthographia 298.6, who has exactly the same gloss as the Suda, though he gives the masculine form λαβρώνιος .