1. verb To teach or educate someone in some area. In this usage, a noun or pronoun is often used between "ground" and "in." I hope to ground my students in a strong knowledge of European history.

2. verb To base or root something, usually a thought or belief, in something in particular. Not one of her accusations is grounded in reality!

3. adjective Deeply embedded. The phrase is usually hyphenated when used as an adjective. Good luck getting those ground-in grass stains out of his pants.

4. adjective Deeply ingrained. The phrase is usually hyphenated when used as an adjective. Good luck getting Phil to change—those bad habits of his sure seem ground-in.