Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
aerūgĭnōsus, a, um, adj. [aerugo], full of copper-rust, rusty (perh. only in Seneca): manus, Contr. 1, 2 fin.: lamellae, id. Brut. Vit. 12.