Isobar(n.) The quality or state of being equal in weight, especially in atmospheric pressure. Also, the theory, method, or application of isobaric science.
Isobar(n.) A line connecting or marking places upon the surface of the earth where height of the barometer reduced to sea level is the same either at a given time, or for a certain period (mean height), as for a year; an isopiestic line.
Isobaric(a.) Denoting equal pressure; as, an isobaric line; specifically, of or pertaining to isobars.

Words within isobars