abruptness vs steepness

abruptness and steepness both are nouns.

Word	Noun	Adjective	Verb	Adverb
abruptness	Yes	No	No	No
steepness	Yes	No	No	No

As nouns, abruptness and steepness are synonyms defined as:

abruptness and steepness: the property possessed by a slope that is very steep

Other synonyms of abruptness include precipitousness.

abruptness (noun)	steepness (noun)
the quality of happening with headlong haste or without warning	the property possessed by a slope that is very steep
the property possessed by a slope that is very steep
an abrupt discourteous manner