Deep definition

Having its bottom far down.
Profound, having great meaning or import, but possibly obscure or not obvious.

That is a deep thought
Seriously or to a significant extent, not superficial.

I just meant to help out a little, but now I'm deep into it

They're deep in discussion

I feel it deep in my heart
In extent in a direction away from the observer.

The shelves are 30cm deep
Thick in a vertical direction.

That cyclist's deep chest allows him to draw more air

There was a deep layer of soot over the window
Voluminous

to take a deep breath / sigh / drink
Low in pitch

She has a very deep contralto
Dark and highly saturated

That's a very deep shade of blue
: of a fielding position near the boundary, or closer to the boundary than one being compared to.

He is fielding at deep mid wicket.
a long way inside

deep into the forest
a long way forward

a deep volley
in a number of rows or layers

A crowd three deep along the funeral procession
difficult to awake

in a deep sleep
right into one's mind

He looked deep into her eyes
with a lot of

deep in debt
Relatively farther downfield.
three deep.

Cigar Pal broke a bit slow, trailed by more than seven lengths after a half-mile, swung three deep into the stretch, rallied from eighth to make up more than four lengths and was nosed out six furlongs on the turf. (Greg Melikov on http://www.sportsbook.com)

:: heavy, meaningful, profound:: thick: great, large, voluminous: low, low-pitched: bright, rich, vivid

: shallow: frivolous, light, shallow, superficial: shallow: shallow, thin: shallow, small: high, high-pitched, piping: light, pale, desaturated, washed-out

(meaning 1 above) part of a lake, sea, etc.

creatures of the deep
The deep (meaning 2 above) part of a problem.
(with "the"): the sea, the ocean
A fielding position near the boundary.

Russell is a safe pair of hands in the deep