Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
tūbĕrōsus, a, um, adj. [tuber], full of humps, lumps, or protuberances (very rare): campus, Varr. R. R. 1, 49, 2: tuberosissima frons, Petr. 15.