isotherm

a. The same as Isocheimal. [ 1913 Webster ]

n. [ Iso- + Gr. &unr_; heat, fr. &unr_; hot. ] 1. (Phys. Geog.) A line connecting or marking points on the earth's surface having the same temperature. This may be the temperature for a given time of observation, or the mean temperature for a year or other period. Also, a similar line based on the distribution of temperature in the ocean. [ 1913 Webster ]

2. (Physics) A line on a graph connecting points representing states having the same temperature; an isothermal line. [ PJC ]

a. [ Cf. F. isotherme. ] (a) Relating to equality of temperature, or an isotherm. (b) (Phys. Geog.) Having reference to the geographical distribution of temperature, as exhibited by means of isotherms; as, an isothermal line; an isothermal chart. [ 1913 Webster ]

Isothermal line. (a) An isotherm. (b) A line drawn on a diagram of energy such that its ordinates represent the pressures of a substance corresponding to various volumes, while the absolute temperature is maintained at a constant value. --
Isothermal zones, spaces on opposite sides of the equator having the same mean temperature, and bounded by corresponding isothermal lines. [ 1913 Webster ]

n. [ Iso- + Gr. &unr_; hot + &unr_; depth. ] (Phys. Geog) A line drawn through points of equal temperature in a vertical section of the ocean. [ 1913 Webster ]