deep

1 of 3

adjective

ˈdēp 

1

: extending far from some surface or area: such as

a

: extending far downward

a deep well

a deep chasm

b(1)

: extending well inward from an outer surface

a deep gash

a deep-chested animal

(2)

: not located superficially within the body

deep pressure receptors in muscles

c

: extending well back from a surface accepted as front

a deep closet

d

: extending far laterally from the center

deep borders of lace

e

sports : occurring or located near the outer limits of the playing area

hit to deep right field

f

sports : thrown or hit for a considerable distance : thrown or hit deep (see deep entry 2 sense 3b)

a deep pass

a deep fly ball

2

: having a specified extension in an implied direction usually downward or backward

a shelf 20 inches deep

cars parked three-deep

3

a

: difficult to penetrate or comprehend : recondite

deep mathematical problems

deep discussions on the meaning of life

b

: mysterious, obscure

a deep dark secret

c

: grave or lamentable in nature or effect

in deepest disgrace

d

: of penetrating intellect : wise

a deep thinker

e

: intensely engrossed or immersed

She was deep in her book.

f

: characterized by profundity of feeling or quality

a deep sleep

also : deep-seated

deep religious beliefs

4

a

of color : high in saturation and low in lightness

a deep red

b

: having a low musical pitch (see pitch entry 4 sense 4b) or pitch range

a deep voice

5

a

: situated well within the boundaries

a house deep in the woods

b

: remote in time or space

found deep in rural England

c

: being below the level of consciousness

deep neuroses

d

: covered, enclosed, or filled to a specified degree

—usually used in combination

ankle-deep in mud

6

: large

deep discounts

7

: having many good players

a deep bullpen

8

computing : having or using many repetitions of algorithmic processing

deep learning

a deep neural network

deeply adverb

deepness noun

deep

2 of 3

adverb

1

: to a great depth : deeply

still waters run deep

tunneled deep into the earth

2

: far on : late

danced deep into the night

3

sports

a

: near the outer limits of the playing area

the shortstop was playing deep

b

: long sense 6

threw deep to the wide receiver

hit the ball deep to right field

deep

3 of 3

noun

1

a

: a vast or immeasurable extent : abyss

b(1)

: the extent of surrounding space or time

the azure deep

(2)

nautical : ocean

the briny deep

2

: any of the deep portions of a body of water

specifically : a generally long and narrow area in the ocean where the depth exceeds 3000 fathoms (5500 meters)

the Aldrich Deep in the south Pacific

3

: the middle or most intense part

in the deep of winter

4

nautical : any of the fathom points on a sounding line other than the marks (see mark entry 1 sense 2b)

Phrases

in deep water

: in difficulty or distress

Synonyms

Adjective

• profound
• vast

Noun

• midst
• middle

Choose the Right Synonym for deep

broad, wide, deep mean having horizontal extent.

broad and wide apply to a surface measured or viewed from side to side.

a broad avenue

wide is more common when units of measurement are mentioned

rugs eight feet wide

or applied to unfilled space between limits.

a wide doorway

broad is preferred when full horizontal extent is considered.

broad shoulders

deep may indicate horizontal extent away from the observer or from a front or peripheral point.

a deep cupboard

deep woods

Examples of deep in a Sentence

Adjective

We walked in the deep snow.

a deep valley between the mountains

The water is deepest in the middle of the lake.

She's afraid of swimming in deep water.

a plant with deep roots

The house has lots of deep closets.

She has a small but deep wound on her arm.

This enormous canyon is over a mile deep.

The shelves are 10 inches deep.

He stepped into an ankle-deep puddle of mud.

Adverb

The ship now lies deep below the water's surface.

Our feet sank deeper into the mud.

The treasure was buried deep within the ground.

Their secret offices were located deep underground.

We walked deep into the forest.

The soldiers are operating deep within enemy territory.

I stood three feet deep in the water.

He stepped ankle-deep into a puddle of mud.

Noun

the kind of cold weather that we usually have only in the deep of winter

sailors exploring the farther reaches of the briny deep

Recent Examples on the Web

Adjective

Tequila has long been celebrated for its deep Mexican heritage and craftsmanship, but Black entrepreneurs, mixologists, and investors are now making their mark on the industry. —Essence, 10 July 2025

Maresca spoke of the importance of this role when playing against teams who like to defend deep — as Fluminense, with 40-year-old former Chelsea captain Thiago Silva in their back line, did here. —Oliver Kay, New York Times, 9 July 2025

Adverb

Roll up your sleeves and dive deep into the best button down shirts Prime Day has to offer. —Kristina Rutkowski, Vogue, 10 July 2025

The video was part of my coverage for this year’s Fortune 500 issue that included an article that dug deep into IBM’s recent rebound. —Sharon Goldman, Fortune, 10 July 2025

Noun

Rick Carlisle routinely stretches his rotation to 11 deep. —Kristian Winfield, New York Daily News, 22 May 2025

New York gave Boston trouble by switching throughout the first two games, rather than playing in this deep of a drop. —James L. Edwards Iii, New York Times, 11 May 2025

Word History

Etymology

Adjective, Adverb, and Noun

Middle English dep, from Old English dēop; akin to Old High German tiof deep, Old English dyppan to dip — more at dip

First Known Use

Adjective

before the 12th century, in the meaning defined at sense 1

Adverb

before the 12th century, in the meaning defined at sense 1

Noun

before the 12th century, in the meaning defined at sense 1b(2)

Phrases Containing deep

• between the devil and the deep blue sea
• deep cut
• deep-dish
• deep dive
• deep down (inside)
• deep ecology
• deep fat
• deep-fat fryer
• deep focus
• deep freeze
• deep-fry
• deep fryer
• deep in debt
• deep learning
• deep pocket
• deep-rooted
• deep-sea
• deep-seated
• deep six
• deep-sky
• deep space
• deep state
• deep structure
• deep temporal artery
• deep throat
• deep web
• go off the deep end
• in deep doo-doo
• in deep shit
• in (too) deep
• jump in (at) the deep end
• knee-deep
• neck-deep
• rapture of the deep
• run deep
• skin-deep
• still waters run deep
• take a deep breath
• the deep
• the deep end
• the deep of the night
• throw in (at) the deep end

Rhymes for deep

• beep
• cheap
• creep
• heap
• jeep
• keep
• leap
• peep
• reap
• seep
• sheep
• sleep

Kids Definition

deep

1 of 3 adjective

ˈdēp 

1

a

: extending far downward

a deep well

b

: having a great distance between the top and bottom surfaces : not shallow

deep water

c

: extending well inward from an outer or front surface

a deep gash

d

: extending far outward from a center

deep space

e

: occurring or located near the outer limits

deep right field

2

: having a specified extension downward or backward

a shelf 40 centimeters deep

3

a

: difficult to understand

a deep book

b

: mysterious, obscure

a deep dark secret

c

: profound sense 1

a deep thinker

d

: completely absorbed

deep in thought

e

: being to an extreme degree : heavy

deep sleep

4

a

: dark and rich in color

a deep red

b

: having a low musical pitch or range

a deep voice

5

a

: coming from or located well within

a deep sigh

a house deep in the forest

b

: covered, enclosed, or filled often to a specified degree

knee-deep in water

a road deep with snow

deeply adverb

deep

2 of 3 adverb

1

: to a great depth : deeply

2

: far on : late

read deep into the night

3

: near the outer limits

the shortstop was playing deep

deep

3 of 3 noun

1

a

: an extremely deep place or part (as of the ocean)

b

: ocean sense 1

2

: the middle or most intense part

the deep of night

Medical Definition

deep

adjective

ˈdēp 

1

a

: extending well inward from an outer surface

a deep gash

b(1)

: not located superficially within the body or one of its parts

deep pressure receptors in muscles

(2)

: resulting from or involving stimulation of deep structures

deep pain

deep reflexes

2

: being below the level of the conscious

deep neuroses

deeply adverb