A 2,000 year old wardrobe staple.
You didn't come here for the Wiki definition although I provided it below. I even call our caftan's, Mrs. Ropers" and they are one of the best things I've ever designed. Maybe it's the kind of thing you have to try to believe just how good they are. But EACH time I wear our caftan out in public someone, a man or woman compliments me. I've worn them to weddings, business meetings and about 1/2 of my Zoom meetings. All the caftans are made from some sort of silk - Italian silk for the Fall/Winter and silk voile for the Spring/Summer. They are elegant and a classic shape from multiple cultures that have been around for hundreds of years. And don't think because the caftan is voluminous that it will make you look bigger. There's something about the hang that will enhance your femininity. They are truly an investment piece.
Try one out.
Ok according to Wikipedia a mumu is - "The muumuu /ˈmuːmuː/ or muʻumuʻu (Hawaiian pronunciation: [ˈmuʔuˈmuʔu]) is a loose dress of Hawaiian origin that hangs from the shoulder and is like a cross between a shirt and a robe. Like the aloha shirt, muumuu exports are often brilliantly colored with floral patterns of generic Polynesian motifs. Muumuus for local Hawaiian residents are more subdued in tone. Muumuus are no longer as widely worn at work as the aloha shirt, but continue to be the preferred formal dress for weddings and festivals such as the Merrie Monarch hula competition. Muumuus are also popular as maternity wear because they do not restrict the waist."
And a caftan, "A kaftan or caftan (/ˈkæftæn/; Persian: خفتان khaftān) is a variant of the robe or tunic, and has been worn in a number of cultures around the world for thousands of years and is of Asiatic origin. In Russian usage, kaftan instead refers to a style of men's long suit with tight sleeves. Used by many West and Southwest Asian ethnic groups, the kaftan is ancient Mesopotamian (modern day Iraq) in origin. It may be made of wool, cashmere, silk, or cotton, and may be worn with a sash. Popular during the time of the Ottoman Empire, detailed and elaborately designed garments were given to ambassadors and other important guests at the Topkapi Palace. Variations of the kaftan were inherited by cultures throughout Asia and were worn by individuals in Russia (North Asia, Eastern Europe and formerly Central Asia), Southwest Asia and Northern Africa  Styles, uses, and names for the kaftan vary from culture to culture. The kaftan is often worn as a coat or as an overdress, usually having long sleeves and reaching to the ankles. In regions with a warm climate, it is worn as a light-weight, loose-fitting garment. In some cultures, the kaftan has served as a symbol of royalty."