An archaic or obsolete term meaning the act of assembling or a gathering of people assembled together.
From Old French 'assemblement', using the -ment suffix (state or result of action) on 'assembler'. This form was common in Middle English but fell out of use.
The -ment suffix was incredibly productive in Middle English—words like 'assemblement' were perfectly normal until they got displaced by simpler forms like 'assembly,' showing how language naturally selects shorter winners.
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