Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Perseus.
raudus (also rōdus and rūdus), ĕris, n. [kindr. with rudis; cf.: crudus, crudelis], a rude mass; hence, in partic., a piece of brass used as a coin (an old word): rodus vel raudus significat rem rudem et imperfectam. Nam saxum quoque raudus appellant poëtae, ut Attius in Menalippo: manibus rapere raudus saxeum grandem et gravem. Vulgus quidem in usu habuit non modo pro aere imperfecto, sed etiam pro signato … in aestimatione censoriă aes infectum rudus appellatur, Fest. s. v. rodus, p. 265 Müll.: aes raudus dictum, Varr. L. L. 5, § 163 ib.: olim aera raudera dicebantur, Val. Max. 5, 6, 3: χαλκὸς ἀνέργαστος rudus, Gloss. Philox.: sculptor ab eris Rudere decoctam consuevit fingere massam, Prud. Apoth. 792: cum rudera milites jacerent, Liv. 26, 11, 9 Weissenb.
rōdus and rōduscŭlum, v. raud-.