extending far down from the top or surface

a deep well; a deep valley.

extending far in or back from the front or from an edge, surface, opening, etc., considered as the front

a deep shelf.

extending far in width; broad

deep lace; a deep border.

ranging far from the earth and sun

a deep space probe.

having a specified dimension in depth

a tank 8 feet deep.

covered or immersed to a specified depth (often used in combination)

standing knee-deep in water.

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.

extending or cutting far down relative to the surface of a given object

The knife made a deep scar in the table.

situated far down, in, or back

deep below the surface; deep in the woods.

reaching or advancing far down

a deep dive.

coming from far down

a deep breath.

made with the body bent or lowered to a considerable degree

a deep bow.

immersed or submerged in or heavily covered with (fol. by in )

a road deep in mud.

difficult to penetrate or understand; abstruse

a deep allegory.

not superficial; profound

deep thoughts.

grave or serious

deep disgrace.

heartfelt; sincere

deep affections.

absorbing; engrossing

deep study.

great in measure; intense; extreme

deep sorrow.

sound and heavy; profound

deep sleep.

(of colors) dark and vivid

a deep red.

low in pitch, as sound, a voice, or the like

deep, sonorous tones.

having penetrating intellectual powers

a deep scholar.

profoundly cunning or artful

a deep and crafty scheme.

mysterious; obscure

deep, dark secrets.

immersed or involved; enveloped

a man deep in debt.

absorbed; engrossed

deep in thought.

Baseball . relatively far from home plate

He hit the ball into deep center field.

Linguistics . belonging to an early stage in the transformational derivation of a sentence; belonging to the deep structure.

the deep part of a body of water, esp. an area of the ocean floor having a depth greater than 18,000 ft. (5400 m).

a vast extent, as of space or time.

the part of greatest intensity, as of winter.

Nautical . any of the unmarked levels, one fathom apart, on a deep-sea lead line. Compare mark 1 ( def. 20 ) .

the deep, Chiefly Literary . the sea or ocean

He was laid to rest in the deep.

to or at a considerable or specified depth

The boat rode deep in the water.

far on in time

He claimed he could see deep into the future.

profoundly; intensely.

Baseball . at or to a deep place or position

The outfielders played deep, knowing the batter's reputation as a slugger.

go off the deep end

to enter upon a course of action with heedless or irresponsible indifference to consequences.

to become emotionally overwrought.

in deep

inextricably involved.

having made or committed oneself to make a large financial investment.

in deep water

in difficult or serious circumstances; in trouble.

in a situation beyond the range of one's capability or skill

You're a good student, but you'll be in deep water in medical school.

adjective

shallow , frivolous , ignorant , superficial , trivial , unintelligent , aboveboard , artless , open , flighty , light , pale , quiet , soft

adjective

abysmal , abyssal , below , beneath , bottomless , broad , buried , deep-seated , distant , downreaching , far , fathomless , immersed , inmost , low , profound , rooted , subaqueous , submarine , submerged , subterranean , sunk , underground , unfathomable , wide , yawning , abstruse , acute , arcane , complex , concealed , delphic , difficult , discerning , esoteric , hard to understand , heavy * , hermetic , hidden , incisive , intricate , learned , mysterious , obscure , occult , orphic , penetrating , recondite , sagacious , secret , serious , sibylline , wise , artful , astute , canny , contriving , crafty , cunning , designing , foxy , guileful , insidious , intriguing , keen , knowing , plotting , sharp , shrewd , sly , tricky , wily , abstracted , centered , concentrated , enfolded , engaged , fixed , focused , intent , into , lost , musing , preoccupied , rapt , set , wrapped , wrapped up , bass , booming , dark , extreme , full-toned , grave , great , hard , low-pitched , low-toned , resonant , rich , sonorous , strong , vivid , intense , alto , contralto , cavernous , endemic , grum , guttural , incomprehensible , inexplicable , ingrained , inveterate , navigable , nethermost , unfathomed

noun

blue * , brine , briny * , davy jones’s locker , drink * , main , middle , ocean , poseidon’s realm , the high seas , abysm , abyss , chasm , depth , gulf , absorbed , abstruse , abstrusity , abysmal , below , bottomless , complete , complex , cunning , dark , entangled , focused , grave , heavy , insidious , intense , intent , involved , low , nadir , penetrating , philosophical , profound , profundity , sea , serious , sly , thorough , vivid