For this headword, a masculine noun, see already omicron 121 (accusative plural) and again omicron 123. LSJ s.v. o)kri/bas lists its bewildering range of attested meanings, including (as II.2) the one apparently noted in the present entry. See further, next note.
[1] The gloss is transmitted as sxh=ma h(nio/xou, but the first noun makes no sense. According to Adler, the Dutch scholar David Ruhnken (1723-1798) proffered the emendation to\ bh=ma 'the platform'; this is ingenious in itself and, rather than necessitating a link with LSJ's sense 1 ('platform or tribune in the Odeum at Athens, on which the actors appeared at the Proagon') attested in e.g. Plato, Symposium 194B (web address 1), it invokes another authentic sense of the noun bh=ma. The headword is identically glossed in the Synagoge, Photius' Lexicon (omicron185 Theodoridis), and Lexica Segueriana 315.29, but (a) Hesychius omicron587 has the gloss bh=ma h(nio/xou (i.e. without Ruhnken's to/), and (b) Adler notes that a manuscript correction in the Lex. Seg. has o)/xhma, i.e. charioteer's support.