Isobar may refer to:
- a contour line of equal or constant pressure in meteorology
- two nuclides with the same mass number in nuclear physics
- a heat pipe
- Isobar (film), a 2007 science fiction film
- Isobar Communications, an international network of digital marketing agencies
Isobar is also linked to:
- Isotope, one of multiple varieties of the same element of different atomic masses
- Isotone, one of multiple nuclides with equal numbers of neutrons
- Isomer, one of multiple molecules with the same formula
- Nuclear isomer, a nuclide in a neutral state (i.e., containing more energy, but with no change in number of protons and neutrons)
