1. a line on a map marking the boundary between regions that differ in a particular linguistic feature, such as pronunciation, vocabulary, or grammar.
Usage: linguistics; used in dialectology and sociolinguistics

Examples

• The isogloss separating the northern and southern dialects runs through the middle of the state.
• Linguists use isoglosses to map out regional variations in speech patterns.
• The pronunciation of 'r' at the end of words follows a clear isogloss in New England.
• Multiple isoglosses can overlap in areas where different dialect features intersect.
• The isogloss for the word 'soda' versus 'pop' shows distinct regional preferences across the country.