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deep

1 deep /ˈdiːp/ adjective
deeper; deepest
1 deep
/ˈdiːp/
adjective
deeper; deepest
Britannica Dictionary definition of DEEP
: having a large distance to the bottom from the surface or highest point
often used figuratively opposite shallow
: going far inward from the outside or the front edge of something
opposite shallow
: located far inside something usually + in or within
often used figuratively
not used before a noun : having a specified measurement downward, inward, or backward
see also skin-deep
: located near the outside edges of an area
: hit, thrown, or kicked a long distance
: done by taking in or breathing out a large amount of air
: low in sound or musical pitch
opposite high
: having a dark, strong color
opposite light, pale
: very intelligent and serious but complex or difficult to understand
: full of mystery
: completely involved in an activity : concentrating and giving all of your attention to something + in
: affected by something in a very serious way + in
10 
: very bad, serious, or severe
11 
: very strongly felt
12 
: full, complete, or thorough
◊ If you are in a deep sleep, you are thoroughly asleep and it is hard to wake you up.
13 
US : going down to a very low price, level, etc.
14 
US, sports : having many good players

in deep water

: in a difficult situation : in trouble

the deep end

informal
used in phrases like throw in (at) the deep end and jump in (at) the deep end to describe starting a new and difficult activity when you are not fully prepared or ready to do it
◊ To go off the deep end is to go crazy, such as by behaving foolishly or by becoming very angry or upset.

— deepness

noun [noncount]
2 deep /ˈdiːp/ adverb
deeper; deepest
2 deep
/ˈdiːp/
adverb
deeper; deepest
Britannica Dictionary definition of DEEP
: far into or below the surface of something
often used figuratively
: far into or inside something
not used before a noun : at a specified measurement downward, inward, or backward
: to a late time
sports
: near the outside edges of a playing area
: for a long distance
◊ If you breathe deep, you take a large amount of air into your lungs.

deep down (inside)

◊ If you feel or believe something deep down or deep down inside, you feel or believe it completely even if you do not say it or show it to other people.

in (too) deep

informal
: in a difficult situation that you cannot get out of

run deep

: to be felt very strongly
see also still waters run deep at 2still
3 deep /ˈdiːp/ noun
3 deep
/ˈdiːp/
noun
Britannica Dictionary definition of DEEP

the deep

literary + formal : the ocean
literary : the middle part of something

the deeps

literary + formal