loosening vs alteration

loosening and alteration both are nouns.

Word	Noun	Adjective	Verb	Adverb
loosening	Yes	No	No	No
alteration	Yes	No	No	No

As nouns, alteration is a hypernym of loosening; that is, alteration is a word with a broader meaning than loosening:

loosening: the act of making something less tight
alteration: the act of making something different (as e.g. the size of a garment)

Other hypernyms of loosening include adjustment, modification.

loosening (noun)	alteration (noun)
the act of making something less tight	the act of revising or altering (involving reconsideration and modification)
an occurrence of control or strength weakening	the act of making something different (as e.g. the size of a garment)
	an event that occurs when something passes from one state or phase to another