chasm vs abyss

chasm and abyss both are nouns.

Word	Noun	Adjective	Verb	Adverb
chasm	Yes	No	No	No
abyss	Yes	No	No	No

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

chasm: a deep opening in the earth's surface
abyss: a bottomless gulf or pit; any unfathomable (or apparently unfathomable) cavity or chasm or void extending below (often used figuratively)

Other hyponyms of chasm include abysm, gulf.

chasm (noun)	abyss (noun)
a deep opening in the earth's surface	a bottomless gulf or pit; any unfathomable (or apparently unfathomable) cavity or chasm or void extending below (often used figuratively)