Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
†† ăros, i, f., also ăron or ărum, i, n., = ἄρον, wake-robin: Arum dracunculus Linn.: quod aron vocant, Plin. 19, 5, 30, § 96; and id. 24, 16, 91, § 142.
ărum, i, v. aros.