Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
2. īlĭăcus, a, um, adj. [ileos], relating to the colic: passio, Cael. Aur. Acut. 2, 17, 171; 3, 21, 206: dolor, 3, 20, 195.
As subst. plur.: īlĭăci, ōrum, m., sufferers from colic, Cael. Aur. Acut. 3, 17, 173.