1. At or to a great depth; far below the surface; as, to sink deeply. 2. Profoundly; thoroughly; not superficially; in a high degree; intensely; as, deeply skilled in ethics. He had deeply offended both his nobles and people. Bacon. He sighed deeply in his spirit. Mark viii. 12. 3. Very; with a tendency to darkness of color. The deeply red juice of buckthorn berries. Bo...