/ ˌrefəˈmeɪʃn; NAmE -fərˈm-/ noun
1.
[ U ] ( formal ) the act of improving or changing sb/sth
2.
the Reformation [ sing. ] new ideas in religion in 16th century Europe that led to attempts to reform the Roman Catholic Church and to the forming of the Protestant Churches; the period of time when these changes were taking place
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WORD ORIGIN
late Middle English : from Latin reformatio(n-) , from reformare shape again, from re- back + formare to form, shape.