cloaca vs sewer

cloaca and sewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
cloaca	Yes	No	No	No
sewer	Yes	No	No	No

As nouns, cloaca and sewer are synonyms defined as:

cloaca and sewer: a waste pipe that carries away sewage or surface water

Other synonyms of cloaca include sewerage.

cloaca (noun)	sewer (noun)
a waste pipe that carries away sewage or surface water	a waste pipe that carries away sewage or surface water
(zoology) the cavity (in birds, reptiles, amphibians, most fish, and monotremes but not other mammals) at the end of the digestive tract into which the intestinal, genital, and urinary tracts open	misfortune resulting in lost effort or money
	someone who sews