cul de sac vs cul

cul de sac and cul both are nouns.

Word	Noun	Adjective	Verb	Adverb
cul de sac	Yes	No	No	No
cul	Yes	No	No	No

As nouns, cul de sac and cul are synonyms defined as:

Other synonyms of cul de sac include dead end.

cul de sac (noun)	cul (noun)
a street with only one way in or out	a passage with access only at one end
a passage with access only at one end