The Collaborative International Dictionary of English v.0.48:

Iliac \Il"i*ac\, a. [Cf. F. iliaque. See Ileum, and cf. Jade
   a stone.]
   1. (Anat.) Pertaining to, or in the region of, the ilium, or
      dorsal bone of the pelvis; as, the iliac artery. [Written
      also ileac.]
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   2. See Ileac, 1. [R.]
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   Iliac crest, the upper margin of the ilium.

   Iliac passion. See Ileus.

   Iliac region, a region of the abdomen, on either side of
      the hypogastric regions, and below the lumbar regions.
      [1913 Webster]