Emily Dickinson Lexicon

IL'I-AC, a. [L. iliacus, from ilia, the flank, or small intestines; Gr. ειλεω, to wind.]

Pertaining to the lower bowels, or to the ileum. The iliac passion is a bad form of ileus or common colic, in which there is inversion of the peristaltic action of the upper part of the small intestines.