adj. having the same pressures, masses, or densities
adj. (of a thermodynamic process) having a constant pressure throughout
the GNU version of the Collaborative International Dictionary of English
adj. Denoting equal pressure
The Century Dictionary and Cyclopedia
Indicating equal weight or pressure, especially the pressure of the atmosphere: in the latter use equivalent to isobarometric.
In mathematics, having all terms of equal weight.
n. In thermodynamics, a line or surface of equal pressures; an isobar.
Word Usage
"The Weather Bureau at Washington relies greatly on these isobars for statements concerning local and distant weather forecasts, any shift in isobaric lines showing change in atmospheric pressure."