Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
nătĭnor, āri, v. dep., to be busy: audito tumultu Macedoniae Samnites, Lucanos inter se natinari atque factiosos esse, Cato ap. Paul. ex Fest. s. v. natinatio, p. 166 Müll.; v. h. v.