2 definitions by WarOnPoorGrammar

The correct expression for "firmly established" or "deeply ingrained."

This is often misheard and misspoken as "deep-seeded" by people who slur their words and pronounce a letter "t" as a "d."

An incorrect expression for "firmly established" or "deeply ingrained."

Seeded is a synonym for "impregnated." Therefore, deep-seeded means "deeply impregnated."