根深柢固

The part of a plant that grows underground; the base or foundation of something; the origin or source of a matter; a classifier for long, thin objects.

Deep; depth; far; very; profound; intense; late; thick; dense; flourishing.

Solid; firm; strong; secure; stable; to strengthen; to consolidate; to fix firmly; to ensure; to be sure; indeed; to be sure; to be certain; to be undoubtedly.