Definitions

1. noun

A line or boundary on a map showing the distribution of a particular language feature, such as a sound or a grammatical construction, across different geographic areas.

“The linguist used isoglosses to chart the spread of a particular dialect across the country.”

2. noun

In ecology, a line or boundary showing the distribution of a particular plant or animal species across different geographic areas.

“The ecologist used isoglosses to study the migration patterns of a particular bird species.”