Definition of: isobar

(ī′sə·bär) noun
1. Meteorol. A line on a chart or diagram connecting places on the earth's surface having the same barometric pressure for a specified time or period.
2. Physics Any of two or more atoms having the same atomic weights but different atomic numbers and chemical properties. [<ISO- + Gk. baros weight]
—i′so·bar′ic (-bar′ik) adjective
—i′so·bar′o·met′ric (-bar′ə·met′rik) adjective