A half-length train on a dress or robe, or a partial train that doesn't extend the full length.
From 'demi-' (half) plus 'train' (from Old French 'traïne'). Fashion terminology from the 17th-18th centuries describing dress styles with shortened trains.
A demitrain was the perfect compromise garment—fancy enough to look impressive but practical enough to actually walk down stairs without tripping, making it wildly popular with women who actually had to work!
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