Isobar \I"so*bar\, n. [Iso- + Gr. ? 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}.]
[1913 Webster]