Definify.com
Webster 1913 Edition
Isobar
I′so-bar
,Noun.
[
Iso-
+ Gr. [GREEK] weight.] (Phys. Geog.)
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.
[Written also
isobare
.]