Nephrolithiasis: The process of forming a kidney stone, a stone in the kidney (or lower down in the urinary tract). Kidney stones are a common cause of blood in the urine and pain in the abdomen, flank, or groin. Kidney stones occur in 1 in 10 people at some time in their life.
The pain with kidney stones is usually of sudden onset, very severe and colicky (intermittent), not improved by changes in position, radiating from the back, down the flank, and into the groin. Nausea and vomiting are common.
"Nephrolithiasis" is derived from the Greek nephros- (kidney) lithos (stone) = kidney stone. The stones themselves are also called renal caluli. The word "calculus" (plural: calculi) is the Latin word for pebble.