tightness vs lack

tightness and lack both are nouns.

Word	Noun	Adjective	Verb	Adverb
tightness	Yes	No	No	No
lack	Yes	No	Yes	No

As nouns, lack is a hypernym of tightness; that is, lack is a word with a broader meaning than tightness:

Other hypernyms of tightness include deficiency, want.

tightness (noun)	lack (noun)
lack of movement or room for movement	the state of needing something that is absent or unavailable
extreme stinginess
the spatial property of being crowded together
a tight feeling in some part of the body
a state occasioned by scarcity of money and a shortage of credit

tightness (verb)	lack (verb)
	be without
	To be insufficiently prepared