aridness vs waterlessness

aridness and waterlessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
aridness	Yes	No	No	No
waterlessness	Yes	No	No	No

As nouns, waterlessness is a hypernym of aridness; that is, waterlessness is a word with a broader meaning than aridness:

aridness: a deficiency of moisture (especially when resulting from a permanent absence of rainfall)
waterlessness: the condition of not containing or being covered by a liquid (especially water)

Other hypernyms of aridness include dryness, xerotes.

aridness (noun)	waterlessness (noun)
a deficiency of moisture (especially when resulting from a permanent absence of rainfall)	the condition of not containing or being covered by a liquid (especially water)