Rare and chiefly dialectal; means ‘to make or become deep(er)’.
Translations
approfondirVerbe rare ou littéraire : rendre plus profond. The workers deeped the channel to allow larger ships.
Les ouvriers ont approfondi le canal pour permettre le passage de plus grands navires.
The workers deeped the channel to allow larger ships.
As the twilight deeped, the stars began to appear.