One of the more unusual articles of clothing I have found in 18th century ancestral estate inventories found in our library at NEHGS is a banyan - a loose morning gown or "robe de chambre," an elegant article of gentleman's clothing principally worn about the house.
The banyan is most famously depicted in the flowing green-blue silk of John Singleton Copley's 1767 portrait of Boston merchant Nicholas Boylston (1716-1771), (above) and its mirrored portrait of his brother, Thomas Boylston (1721-1798), at the Harvard Art Museums, Cambridge, Massachusetts. Influenced by eastern traditions, this "fashionably exotic attire," the museum states, "would have carried tremendous symbolic power in mid-eighteenth century Boston." The Boylstons also wear another essential ingredient of the merchant prince's banyan wardrobe: a puffy turban-like silk cap, jauntily askew.
Here is an interesting inventory of historic banyans from museum collections and elsewhere: