Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dē-nascor, nasci, v. dep., to perish, die (ante-class. and rare), opp. nasci, Varr. L. L. 5, § 70 Müll.; 21; Cass. Hem. ap. Non. 101, 29 ( = decrescere, Non.).