Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† dĕcēris, is, f., = δεκήρης (sc. ναῦς), a ten-oared ship, i. e. a ship having ten banks of oars: Liburnicas, Suet. Calig. 37 (acc. to a conject. of Turneb. Adv. 22, 30; lect. vulg. de cedris).