https://www.bbc.com/news/world-44569277 https://www.bbc.com/news/world-44569277 > Typically native speakers know 15,000 to 20,000 word families - or lemmas - i

https://www.bbc.com/news/world-44569277 https://www.bbc.com/news/world-44569277 > Typically native speakers know 15,000 to 20,000 word families - or lemmas - in their first language. Sounds about right to me.