Entry 3 senses · 2 variants Webster, 1913 Iliac · Il·i·ac · IPA /ˈɪliæk/ a. a. 01 a. Pertaining to ancient Ilium, or Troy. 1. Pertaining to ancient Ilium, or Troy. 02 a. Pertaining to, or in the region of, the ilium, or dorsal bone of the pelvis; as, the iliac artery. 1. Pertaining to, or in the region of, the ilium, or dorsal bone of the pelvis; as, the iliac artery.(Anat.) 2. See Ileac, 1.[R.] See: Ileac Phrases & compounds 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.