Answer:

deep

Answer	Crossword Clue
DEEP	Difficult to understand
DEEP	Not shallow
DEEP	Word with freeze or pit

DEEP	.. Blue (Kasparov foe of '96)
DEEP	Abysmal
DEEP	How still waters run
DEEP	Profound
DEEP	Like things that make you go "hmm ..."
DEEP	"You just blew my mind, dude"
DEEP	Super philosophical, man
DEEP	Like a fat cat's pockets

DEEP	Thought-provoking
DEEP	Way down
DEEP	Insightful
DEEP	Full of insight
DEEP	Abstruse
DEEP	Cavernous
DEEP	Difficult to fathom
DEEP	Hard to fathom

DEEP	Inscrutable
DEEP	Like one end of many a pool
DEEP	Like a philosopher
DEEP	Like corporate "pockets"
DEEP	Bass
DEEP	Thoughtful
DEEP	..-sea
DEEP	Hardly superficial

DEEP	Requiring much thought
DEEP	Word before freeze or fry
DEEP	Benchley novel "The .."
DEEP	Far beneath the surface
DEEP	Like the diving-board end
DEEP	Sea, with "the"
DEEP	Serious
DEEP	"... Impact" ('98 disaster film)

DEEP	Hard to understand, as a math problem
DEEP	Heartfelt
DEEP	Requiring a lot of thought
DEEP	Watergate's ... Throat
DEEP	Word with freeze or fry