caldera (n.)

"cavity on the summit of a volcano," 1865, from Spanish caldera, literally "cauldron, kettle," from Latin caldarium "hot-bath" (plural caldaria), from caldarius "pertaining to warming," from calidus "warm, hot" (from PIE root *kele- (1) "warm").

The term was originally used in describing volcanic regions occurring where Spanish is the current language, and was introduced by Von Buch in his description of the Canaries. [Century Dictionary]