Cap sleeve

Look at the armhole. A cap sleeve is a small extension of the bodice or a tiny set-in sleeve that stops on the shoulder or at the top of the upper arm. The underarm is open. You should not see a full short-sleeve hem around the biceps.

It can be cut in one with the bodice or seamed as a miniature sleeve. It is not sleeveless (no shoulder coverage) and not a puff (no gathered volume).[1]

Sleeve length in modern English runs from this barely-there cap to floor-length hanging sleeves such as the Japanese furisode.[1] The cap sleeve is a twentieth-century ready-to-wear solution: it gives the look of a sleeve and covers the shoulder strap or bra line without adding fabric on the arm.

It became common on Western women’s day dresses, evening gowns that needed a little more coverage than a strap, and later on T-shirts and knits. Photographs of mid-century summer fashion shows often record cap-sleeved cotton dresses.[1] The construction is simple, so it travels easily through mass manufacturing. It has no single inventor and no city of origin in the way Peter Pan or raglan names do; the term describes the shape (a cap over the shoulder) rather than a person or regiment.[1]

Related historical sleeves are longer or fuller: the 1820s–1890s gigot and puff, Renaissance hanging sleeves, and medieval set-in sleeves. The cap sleeve sits at the opposite extreme—minimum coverage, minimum bulk.[1]

Typical uses are warm-weather dresses, cocktail and wedding-guest dresses that must cover the shoulder, knit tees, and formal gowns that cannot be strapless. It is less used in tailored menswear and in workwear that needs sun or abrasion protection on the arm.[1]

It is a day-to-evening fashion device more than a uniform feature, aside from some hospitality or pageant dresses.

What is worn now: sundresses, sheath dresses, jersey tops, and bridal or bridesmaid dresses with a narrow cap over the shoulder. Athletic and logo tees sometimes use a slightly dropped cap.

Choose a cap sleeve when you want the arm bare but the shoulder finished. If the “cap” reaches mid-bicep, it is a short sleeve, not a cap.[1] Structured woven caps can stick out like little wings; knit caps usually hug the shoulder. A cardigan or jacket over a cap-sleeve dress converts it for air-conditioned rooms.

Sleeveless leaves the shoulder edge of the bodice as the finish. A cap covers that edge. A short sleeve continues below the armpit around the arm. A puff sleeve is gathered and stands away from the arm even when it is also short.[1]

A raglan sleeve is defined by a diagonal seam to the neckline, not by length; raglans can be cap-length but usually are not.[1]

Cap sleeves look light, summery, and slightly dressy compared with a tank strap. They can also look unfinished if the cap is tiny and floppy. On eveningwear they read as modest relative to strapless, without adding the formality of a full sleeve.

Is a cap sleeve the same as sleeveless? No. Sleeveless has no sleeve. A cap sleeve covers the shoulder, even if it is only a few centimeters deep.[1]

Does it hide the underarm? Usually not. The opening sits at armpit level by definition.[1]

When did it appear? As a named ready-to-wear length it belongs to twentieth-century Western dress, not to the exaggerated puffs of the 1830s or 1890s.[1]