Definition of deep
(Entry 1 of 3)
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
3a : 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
4a 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
5a : 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 combinationankle-deep in mud
6 : large deep discounts
7 : having many good players
a deep bullpen
in deep water
: in difficulty or distress
deep
adverbDefinition of deep (Entry 2 of 3)
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
nounDefinition of deep (Entry 3 of 3)
1a : a vast or immeasurable extent : abyss
b(1) : the extent of surrounding space or time
the azure 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)
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
Slippery Words Quiz—Changing with the Times
- What is an earlier meaning of nice?

Test your visual vocabulary with our 10-question challenge!
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
Slippery Words Quiz—Changing with the Times
Do you know these earlier meanings of words?
Take the quizWords of Snow and Ice Quiz
A selection of words from the chillier parts of t...
Take the quizName That Thing
Test your visual vocabulary with our 10-question ...
Take the quizWord Winder's CrossWinder Play the game
Share deep
Time Traveler for deep
The first known use of deep was before the 12th century
See more words from the same century