tough luck vs sewer

tough luck and sewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
tough luck	Yes	No	No	No
sewer	Yes	No	No	No

As nouns, sewer is a hyponym of tough luck; that is, sewer is a word with a more specific, narrower meaning than tough luck:

Other hyponyms of tough luck include weakness, adversity, hard knocks, hardship, gutter, toilet, hard cheese.

tough luck (noun)	sewer (noun)
an unfortunate state resulting from unfavorable outcomes	a waste pipe that carries away sewage or surface water
	misfortune resulting in lost effort or money
	someone who sews