Meaning of “deep” - Learner’s Dictionary

deep

adjective uk us /diːp/
TOP TO BOTTOM

A2 having a long distance from the top to the bottom:

The water is a lot deeper than it seems.
FRONT TO BACK

having a long distance from the front to the back:

How deep are the shelves?
one metre/6 ft, etc deep

B2 one metre/6 ft, etc from the top to the bottom, or from the front to the back:

This end of the pool is two metres deep.
FEELING

B2 A deep feeling is very strong:

SOUND

B2 A deep sound is low:

a deep voice
SERIOUS

serious and difficult for most people to understand:

a deep sleep

B2 sleep that it is difficult to wake someone from

COLOUR

B1 A deep colour is strong and dark:

deep brown eyes
take a deep breath

B2 to fill your lungs with air:

Take a deep breath and relax.
deep in thought/conversation

giving all of your attention to what you are thinking or talking about, and not noticing anything else

→ See also throw sb in at the deep end , be in deep water

(Definition of “deep adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)