ISOBARS

Noun

isobars

plural of isobar

Source: Wiktionary

ISOBAR

I"so*bar, n. Etym: [Iso- + Gr. (Phys. Geog.)

Definition: 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.]

I"so*bar, n.

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

Source: Webster’s Unabridged Dictionary 1913 Edition