The headword, evidently quoted from somewhere, is the aorist passive participle, masculine nominative (and vocative) singular, of the verb r(w/nnumi, I strengthen; see generally LSJ s.v. It occurs at e.g. Plato, Symposium 210D (web address 1), where Socrates (sigma 829) recalls the teachings of the priestess Diotima (OCD(4) s.v.).
[1] The gloss is the same verbal form of dunamo/w, I empower; see generally LSJ s.v., and cf. ps.-Herodian, Partitiones 120; and rho 263. Adler also cites Ambrosian Lexicon 249.