tallness vs lowness

tallness and lowness both are nouns.

Word	Noun	Adjective	Verb	Adverb
tallness	Yes	No	No	No
lowness	Yes	No	No	No

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

tallness: the vertical dimension of extension; distance from the base of something to the top
lowness: the quality of being low; lacking height

Other hyponyms of tallness include highness, loftiness.

tallness (noun)	lowness (noun)
the vertical dimension of extension; distance from the base of something to the top	the quality of being low; lacking height
the property of being taller than average stature	a low or small degree of any quality (amount or force or temperature etc.)
	a feeling of low spirits
	a position of inferior status; low in station or rank or fortune or estimation