Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
subverbustus, a, um, adj. [perhaps contr. from sub verubus ustus], branded under the spear, an epithet of a male or female slave (ante- and post-class.): subverbustam veribus ustam significat Plautus cum ait: ulcerosam, compeditam, subverbustam, sordidam, Fest. p. 309 Müll.; Tert. Pall. 4 med.