1. a. Extending far downward below a surface: a deep hole in the river ice. b. Extending far inward from an outer surface: a deep cut. c. Extending far backward from front to rear: a deep walk-in refrigerator. d. Extending far from side to side from a center: a deep yard surrounding the house. e. Far distant down or in: deep in the woods. f. Coming from or penetrating to a depth: a deep sigh. g. Sports. Located or taking place near the outer boundaries of the area of play: deep left field.

2. Extending a specific distance in a given direction: snow four feet deep.

3. Far distant in time or space: deep in the past.

4. a. Difficult to penetrate or understand; recondite: a deep metaphysical theory. b. Of a mysterious or obscure nature: a deep secret; ancient and deep tribal rites. c. Very learned or intellectual; wise: a deep philosopher. d. Exhibiting great cunning or craft: deep political machinations.

5. a. Of a grave or extreme nature: deep trouble; deepest deceit. b. Very absorbed or involved: deep in thought; deep in financial difficulties. c. Profound in quality or feeling: a deep trance; deep devotion.

6. Rich and intense in shade. Used of a color: a deep red.

7. Low in pitch; resonant: a deep voice.

8. Covered or surrounded to a designated degree. Often used in combination: waist-deep in the water; ankle-deep in snow.

9. Large in quantity or size; big: deep cuts in the budget.

1. To a great depth; deeply: dig deep; feelings that run deep.

2. Well along in time; late: worked deep into the night.

3. Sports. Close to the outer boundaries of the area of play: played deep for the first three innings; ran deep into their opponents' territory.

1. a. A deep place in land or in a body of water: drowned in the deep of the river. b. A vast, immeasurable extent: the deep of outer space.

2. The extent of encompassing time or space; firmament.

3. The most intense or extreme part: the deep of night.

4. The ocean.

5. Nautical. A distance estimated in fathoms between successive marks on a sounding line.