goniometer /ˌɡoʊ.niˈɔ.mə.tɚ/ noun5 •A device used to measure angles. •A device used to measure the angles of joints commonly used in orthopedics and physical therapy. •A device used to measure the angles of crystals. •An arthrometer (device for measuring the arc or range of mobility of a joint). •A radio direction finder. formsgoniometers