gook vs sapropel

gook and sapropel both are nouns.

Word	Noun	Adjective	Verb	Adverb
gook	Yes	No	No	No
sapropel	Yes	No	No	No

As nouns, sapropel is a hyponym of gook; that is, sapropel is a word with a more specific, narrower meaning than gook:

gook: any thick, viscous matter
sapropel: sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans

gook (noun)	sapropel (noun)
any thick, viscous matter	sludge (rich in organic matter) that accumulates at the bottom of lakes or oceans