root

The underground part of a plant that anchors it and absorbs water.

"The tree's roots spread wide."

The fundamental source or origin from which something develops or arises.

"We must find the root of the problem."

To establish deeply and firmly in a place, idea, or tradition.

"The custom is deeply rooted in history."

To support or cheer enthusiastically for a team or person.

"We rooted for our local football team."