Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
guttŭrōsus, a, um, adj. [guttur], that has a tumor in the throat, goitred (postclass.): si quis naturā gutturosus sit, Dig. 21, 1, 12, § 2; Paul. ex Fest. 112, 2; Schol. Juv. 13, 162; cf. guttur.