Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
aerōsus, a, um, adj. [aes], full of copper: Cyprus, Paul. ex Fest. p. 20 Müll.: aurum, gold that contains many parts of copper, Plin. 33, 5, 29, § 93: ferrum, id. 34, 14, 41, § 143: pecunia, Dig. 46, 3, 102.