Definition of Deep

Adjective: deep (deeper,deepest) deep

Not easily disturbed or changed; big or strong
"a deep breath"; "a deep sigh"; "deep concentration"; "deep emotion"; "a deep trance"; "in a deep sleep"
Marked by depth of thinking
"deep thoughts"; "a deep allegory"
Having great spatial extension or penetration downward or inward from an outer surface or backward or laterally or outward from a centre; sometimes used in combination
"a deep well"; "a deep dive"; "deep water"; "a deep casserole"; "a deep gash"; "deep massage"; "deep pressure receptors in muscles"; "deep shelves"; "a deep closet"; "surrounded by a deep yard"; "hit the ball to deep centre field"; "in deep space"; "waist-deep"
Very distant in time or space
"deep in the past"; "deep in enemy territory"; "deep in the woods"; "a deep space probe"
Extreme
"in deep trouble"; "deep happiness"
Having or denoting a low vocal or instrumental range
"a deep voice";
- bass
Strong; intense
"deep purple";
- rich
Relatively thick from top to bottom
"deep carpets"; "deep snow"
Extending relatively far inward
"a deep border"
(of darkness) very intense
"a face in deep shadow"; "deep night";
- thick
Large in quantity or size
"deep cuts in the budget"
With head or back bent low
"a deep bow"
Of an obscure nature
"a deep dark secret";
- cryptic, cryptical, inscrutable, mysterious, mystifying
Difficult to penetrate; incomprehensible to one of ordinary understanding or knowledge
"a deep metaphysical theory";
- abstruse, recondite
Exhibiting great cunning usually with secrecy
"deep political machinations"; "a deep plot"

Adverb: deep deep

To a great depth;far down
"dug deep";
- deeply
To an advanced time
"deep into the night";
- late
To a great distance
"penetrated deep into enemy territory"; "went deep into the woods"

Noun: deep deep

The central and most intense or profound part
"in the deep of night"; "in the deep of winter"
A long steep-sided depression in the ocean floor
- trench, oceanic abyss
Literary term for an ocean
"denizens of the deep"