isobutylphenyl propionic acid n 1: a nonsteroidal anti-inflammatory and analgesic medicine (trade names Advil and Motrin and Nuprin) used to relieve the pain of arthritis and as an antipyretic; "daily use of ibuprofen can irritate the stomach" [syn: {ibuprofen}, {isobutylphenyl propionic acid}, {Advil}, {Motrin}, {Nuprin}]