What is "chronolect"

n. A specific variety of a language at a given time in its history of development.

In linguistics, a chronolect is a specific variety of language of which the characteristics are in particular determined by time-related factors. As such, it can be contrasted with a sociolect, an ethnolect or a geolect. In historical linguistics, a chronolect is set more or less equal to a specific language stage. Many chronolects are extinct or endagered.