<p><strong>Adjective</strong></p><ul><li>extending far down from the top or surface: a deep well; a deep valley.</li><li>extending far in or back from the front or from an edge, surface, opening, etc., considered as the front: a deep shelf.</li><li>extending far in width; broad: deep lace; a deep border.</li><li>ranging far from the earth and sun: a deep space probe.</li><li>having a specified dimension in depth: a tank 8 feet deep.</li><li>covered or immersed to a specified depth (often used in combination): standing knee-deep in water.</li><li>having a specified width or number of items from front to back (often used in combination): shelves that are 10 inches deep; cars lined up at the entrance gates three-deep.</li><li>extending or cutting far down relative to the surface of a given object: The knife made a deep scar in the table.</li><li>situated far down, in, or back: deep below the surface; deep in the woods.</li><li>reaching or advancing far down: a deep dive.</li><li>coming from far down: a deep breath.</li><li>made with the body bent or lowered to a considerable degree: a deep bow.</li><li>immersed or submerged in or heavily covered with (followed by in): a road deep in mud.</li><li>difficult to penetrate or understand; abstruse: a deep allegory.</li><li>not superficial; profound: deep thoughts.</li><li>grave or serious: deep disgrace.</li><li>heartfelt; sincere: deep affections.</li><li>absorbing; engrossing: deep study.</li><li>great in measure; intense; extreme: deep sorrow.</li><li>sound and heavy: deep sleep.</li><li>(of colors) dark and vivid: a deep red.</li><li>low in pitch, as sound, a voice, or the like: deep, sonorous tones.</li><li>having penetrating intellectual powers: a deep scholar.</li><li>profoundly cunning or artful: a deep and crafty scheme.</li><li>mysterious; obscure: deep, dark secrets.</li><li>immersed or involved; enveloped: a man deep in debt.</li><li>absorbed; engrossed: deep in thought.</li><li>Baseball: relatively far from home plate: He hit the ball into deep center field.</li><li>Linguistics: belonging to an early stage in the transformational derivation of a sentence; belonging to the deep structure.</li></ul><p><strong>Noun</strong></p><ul><li>the deep part of a body of water, especially an area of the ocean floor having a depth greater than 18,000 feet (5,400 meters).</li><li>a vast extent, as of space or time.</li><li>the part of greatest intensity, as of winter.</li><li>Nautical: any of the unmarked levels, one fathom apart, on a deep-sea lead line.</li><li>Compare mark 1 (def 20).</li><li>the deep, Chiefly Literary: the sea or ocean: He was laid to rest in the deep.</li></ul><p><strong>Adverb</strong></p><ul><li>deep·er, deep·est: to or at a considerable or specified depth: The boat rode deep in the water.</li><li>far on in time: He claimed he could see deep into the future.</li><li>profoundly; intensely.</li><li>Baseball: at or to a deep place or position: The outfielders played deep, knowing the batter's reputation as a slugger.</li></ul>