say it: awl-tur-AY-shuhn
alteration is a noun meaning "an event that occurs when something passes from one state or phase to another". It carries 3 recorded senses.
an event that occurs when something passes from one state or phase to another
“the change was intended to increase sales”
“this storm is certainly a change for the worse”
“the neighborhood had undergone few modifications since his last visit years ago”
the act of making something different (as e.g. the size of a garment)
the act of revising or altering (involving reconsideration and modification)
“it would require a drastic revision of his opinion”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for alteration come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.