define diverticulitis
diverticulitis in Medicine Expand. diverticulitis diÂ·verÂ·ticÂ·uÂ·liÂ·tis (dÄ«'vÃ»r-tÄ­k'yÉ-lÄ«'tÄ­s) n. Inflammation of a diverticulum, especially of the small pockets in the wall of the colon that fill with stagnant fecal material and become inflamed. diverticulitis. Inflammation of a diverticulum or of diverticula in the intestinal tract, usually causing abdominal pain and fever.