alteration vs loosening

alteration and loosening both are nouns.

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

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

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

Other hyponyms of alteration include laxation, tightening, accommodation, adaptation, tune.

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