Main Entry: iso·therm

Pronunciation: \ˈī-sə-ˌthərm\

Function: noun

Etymology: French isotherme, adjective

Date: 1859

1 : a line on a map or chart of the earth's surface connecting points having the same temperature at a given time or the same mean temperature for a given period
2 : a line on a chart representing changes of volume or pressure under conditions of constant temperature