cappuccino

PIE word
*káput
Borrowed from Italian cappuccino (“cappuccino (coffee drink)”), from Viennese German Kapuziner (“Capuchin (member of an order of Roman Catholic friars)”) (due to the similarity of the dark brown colour of the beverage to that of the monastic habit; compare Franziskaner (“Franciscan”), a contemporary coffee drink with more milk and hence a lighter colour, similar to Franciscan monks’ light brown habits), and café noisette. Kapuziner was in turn borrowed from Italian cappuccino (“Capuchin”), from Italian cappuccio (“cowl, hood”) (from the hoods of Capuchin monks’ habits) + -ino (diminutive suffix); and cappuccio from cappa (“cowl, hood; cape, cloak; sleeveless coat”) (from Late Latin cappa (“cape; sleeveless coat”); further etymology uncertain, perhaps from Proto-Indo-European *káput (“head”)) + -uccio (“diminutive suffix”). Doublet of Capuchin.
The plural form cappuccini is derived from Italian cappuccini.
details
In English attested 1904 as “[small] coffee mixed with milk”, 1933 as “express strong coffee diluted with milk”; in Italian 1905 as “black coffee ‘corrected’ with milk”, and still in 1931 as “black coffee mixed with a little milk”; the modern sense of a coffee drink made with espresso at a bar presumably developed in the 1930s in Italian, and was borrowed into English. The Italian term is of Northern Italian origin, in areas of former or contemporary Austrian rule and influence. The German term Capuzinerkaffee (Capuchin coffee) is attested 1790, referring to a rather different drink (boiled coffee with cream, sugar, spice, and whisked eggs), though by 1848 and into the early 1900s the Kapuziner had come to mean a drink of coffee and milk, with more coffee than milk, by contrast with the Melange, which had more milk than coffee; this usage continues to the present.
The etymology is confusing for a number of reasons. Firstly, the sense of “coffee beverage” originated in German, not in Italian, but the word (in the sense “Capuchin monk”) was calqued from Italian into German and then the sense of “coffee beverage” was reborrowed back into Italian. Secondly, the beverage that it refers to has changed over time: the modern international beverage is based on the Italian espresso-based, milk foam-topped drink of the mid-1900s, not the Viennese drink of coffee plus milk or cream from the 1800s; in Viennese coffeehouses, the Kapuziner and Franziskaner are still served, while the Viennese equivalent of the modern foam-topped cappuccino is the Melange. Thirdly, the association of the word with the drink is sometimes (erroneously) believed to be due to the “cap” of foam in the modern espresso-based form of the drink, though at the time the word was coined (in the 1700s) the drink only consisted of adding milk or cream to coffee: espresso machines date to the 1880s and foam-topped cappuccinos date to the mid-1900s, long after the word was established.