isobar

n. line on a weather map or chart that connects areas of equal barometric pressure (Meteorology)

The word isobar derives from the two ancient Greek words, ισος (isos), meaning 'equal', and βαρος (baros), meaning 'weight'.In meteorology, thermodynamics, and similar science (and engineering), an isobar is a contour line of equal or constant pressure on a graph, plot, or map. (For further discussion, see under Contour line)In nuclear physics, two nuclides with the same mass number are called isobars. For example, boron-12 and carbon-12 are isobars.Isobar has also occasionally been used as a synonym for a heat pipe.Isobar is the title of a 2007 science fiction film.Isobar is an international network of digital marketing agencies.
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Noun
1. an isogram connecting points having equal barometric pressure at a given time
(hypernym) isogram, isopleth, isarithm

(n.)
The quality or state of being equal in weight, especially in atmospheric pressure. Also, the theory, method, or application of isobaric science.
  

(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.
  

A line connecting points of equal pressure.