Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
hĕbĕtātĭo, ōnis, f. [hebeto], dulness, dimness: oculorum, Plin. 28, 6, 16, § 58: nascitur ex assiduitate laborum animorum hebetatio quaedam ac languor, Sen. Tranq. An. 15, 12.