verb/ɑ̃.fɔ̃.se/
to push in, to press in, to drive in; to break open, to break down; to defeat, to thrash; to sink down; to bury oneself; to immerse oneself
“Ouvrez, ou j'enfonce la porte.” — Open up, or I'll break down the door.
From en- + fond + -er.