1. a line on a map or chart connecting points of equal atmospheric pressure at a given time or on average over a period
Usage: meteorology; commonly used in weather forecasting and analysis
2. each of two or more atoms of the same element that have the same mass number but different atomic numbers
Usage: chemistry; physics; rare in general usage

Examples

• The weather forecast showed isobars clustered tightly together, indicating strong winds.
• Meteorologists use isobars to identify high-pressure and low-pressure systems.
• The isobars on the map revealed a developing storm system moving eastward.
• In chemistry, isobars are atoms with the same mass number but different numbers of protons.
• The spacing between isobars tells us how rapidly pressure changes across a region.