The headword, presumably extracted from the quotation given, is the masculine/neuter dative singular of the adjective pollosto/s; cf. pi 1925 and see LSJ s.v., esp. sense II there (web address 1).
[1] Quotation unidentifiable. As Adler notes, Bernhardy, citing sou ('your'), suggested that the passage was corrupt unless the genitive singular participle prou)/contos were to be replaced with the dative prou)/conti. But the enclitic form of the pronoun sou= is used in an unemphatic context [Smyth 325a], which is plausible in the passage. However, it is impossible to be certain of the meaning here.