| Definition -
The hypothesis that all human languages derive from a single source language.
1. As opposed to polygenesis, which hypothesizes that unrelated languages emerged spontaneously at different places and at different times.
2. If you believe this, you are a monogenist.
Etymology - No one knows who coined the term — which means "single birth" in Greek — but the concept was popularized by Alfredo Trombetti in his 1905 book L'unità d'origine del linguaggio, the first serious attempt prove its possibility.
Oxford English Dictionary - Its first English citation is from 1936:
"At various times scholars have raised the question of monogenesis as opposed to polygenesis of human speech: whether it had a single origin at a given time and place, whence it spread over the rest of the earth, or whether it was independently evolved by different branches of the human family."
(Science & Society I. 23)