to·phus 
(tōfəs)
(tōfəs)n. pl. to·phi (-fī)
1. A deposit of urates in the skin and tissue around a joint or in the external ear, occurring in gout. Also called chalkstone.
2. A concretion of mineral salts and organic matter deposited on the surface of the teeth.
[Latin tōphus, tufa.]