Is it ensure, insure, or assure?
late 14c., from Old French reumatique (Modern French rhumatique), from Latin rheumaticus "troubled with rheum," from Greek rheumatikos, from rheuma "discharge from the body" (see rheum).
rheumatic rheu·mat·ic (rōō-māt'ĭk)adj. Relating to or characterized by rheumatism. n. One who is affected by rheumatism.