The headword is a feminine noun in the accusative singular; see generally LSJ s.v. o(lkh/ (pulling, dragging, tugging towards). [Another sense is a drawing-down (of a scale, i.e. a weight); so already omicron 173.] It must be quoted from somewhere; Theodoridis [see next note] mentions Naber's view that the source is Plato, Philebus 57D (figurative there).
[1] The glosses are the same form as the headword; see LSJ s.vv. e)pagwgh/ and troph/. The headword is identically glossed in the Synagoge, Photius' Lexicon (omicron226 Theodoridis), and Lexica Segueriana 316.19.