'enactment' originates from late Middle English, formed from the verb 'enact' + the noun-forming suffix '-ment' (from Old French '-ment'). 'Enact' itself comes via Middle English 'enacten' from Old French 'enacter', ultimately related to Latin roots for 'act' (from 'actus', past participle of 'agere', "to do").

'enact' changed from Middle English 'enacten' and Old French 'enacter' and, with the addition of '-ment', eventually became the modern English noun 'enactment'.

Initially, it meant primarily 'the act of making into law' or 'a law that has been made'; over time it has retained that legal sense while also being used for 'the act of performing or representing' (as in staged reenactments).