Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† ăcŏrus, i, f., and ăcŏrum, i, n., = ἄκορος and ἄκορον, an aromatic plant, conjectured by some to be our sweet-flag or calamus, Plin. 25, 13, 100, § 157 sq.; 26, 5, 15, § 28; Cels. 3, 21; 2, 23 al. In the form acoros, i, f., App. Herb. 6.