Coverage swimwear is enjoying a glorious moment, from high-waisted bikini bottoms to long-sleeved one-pieces — and sun protection, whatever form it takes, is inarguably a good idea. But one surprising coverage style has been staging a quiet comeback of late.

Urban Outfitters calls it a cami top. Melissa Odabash, Madewell, Ward Whillas, and Cynthia Rowley call it a rash guard or a rash vest.

The rash guard — functionally, a long T-shirt made of stretchy bathing suit material — has long been worn by kids, the sun-sensitive, and athletes. Its named function is to protect against rashes incurred from a board, be it surf or boogie; it’s also commonly used to shield skin from the sun. But for a rash guard to end several inches above the wearer’s bikini bottoms, as these do, would defeat both purposes. This reemergent style, no matter how fervently labels’ marketing departments may wish it, is not that.

At least Trina Turk, Outdoor Voices, and Target, three of the many retailers that have included the style in their summer swim collections, have summoned the gumption to call it by its true name: tankini.

Why might it require gumption to speak the word “tankini” aloud? We are, after all, only referring to a long bikini top paired with a standard bikini bottom, each made of swimsuit material. The top can be tight or fluttery; it can even cover the shoulders, making it less of a tank and more of a shirt. As with pornography, one identifies the tankini from a deep knowing. For while the Encyclopedia of Clothing and Fashion defines the tankini as “a two-piece that can provide as much coverage as a one-piece,” it has its own ineffable if potent sensibility.

Neither fully insouciant nor fully pragmatic, the tankini is swimwear in purgatory.

Carl Sagan famously wrote in Cosmos, “If you want to create an apple pie from scratch, you must first create the universe.” If you want to understand the tankini, it is not enough to travel back to the late 1990s, when the tankini first enjoyed popular circulation in the United States, nor even to Paris in 1946, when Louis Réard shot model Micheline Bernardini in a high-cut bikini, freeing the navel and scandalizing polite society.

To truly understand the tankini, we must travel first to an Italian island in the fourth century and southern England in the 18th century, if only briefly.

Here we are: Villa Romana del Casale, the extraordinary Sicilian palace and UNESCO World Heritage Site packed with mosaics. The mosaic of interest is on the floor of a small room called the Sala delle Dieci Ragazze (“Room of the 10 Girls”); it depicts ancient women lifting weights and throwing balls in spare two-pieces. While more function than fashion, the girls’ brown draped bottoms offer subtle One Million Years B.C., Raquel Welch-in-the-surf-holding-a-spear energy.

And here also: The chilly sand beaches of Margate, Kent, where Benjamin Beale, a Quaker and clothing maker, enhanced the “bathing machines” that his countryfolk had seen in France starting a century earlier. (English diarist John Evelyn recorded, “On the 2nd of August, 1651, I went with my wife to Conflans, where were abundance of ladys and others, bathing in the river; the ladys had their tents spread on the water for privacy.”) While the bathing machine had functioned as an in-sea changing room, often drawn into the water by horses, Beale added an awning, a.k.a. a “modesty hood.” Not only could users now enter the ocean privately, they could conceal their entire experience. Beale gave unwieldy physical form to what laws and customs had long made known: Even contained in water, the female body is liability.

Books have been written and museum exhibits have been staged on the history of swimwear. We’re skipping the flannel bathing gown and the nude moments and the Spanx-esque playsuit garments that women wore in the Olympics …

But the tankini’s sensibility lies between the mosaic and the machine. The mosaic’s woman: in free motion, male gaze be damned. The machine’s woman: shielded and constrained, damned by the male gaze.

“If a woman is going to buy a new suit this season, it’s going to be a tankini,” Macy’s fashion director told Newsday in 1999. Designer Anne Cole, who is widely credited with having introduced the tankini to market, claimed the style raised her overall sales 30 percent. It met a national need, both for the parents of teen girls who wanted a stopgap before the string bikini and for adult women who desired just a bit of freedom and quite a bit of coverage. Noting this early success, designers across price points quickly followed Cole’s lead; in a major moment in tankini history, Kate Moss sported a chic Gucci number on the May 1998 cover of Harper’s Bazaar. The tankini infiltrated both high and popular culture, from William Safire’s “On Language” column to Walmarts and water parks.

But by 2001, the New York Times reported the tankini was on the decline, and come the mid-aughts, the swimwear seemed less zeitgeist, more relic. While tankinis have remained on offer in the intervening decades, they’ve faded as a “style,” relegated to retailers like Athleta, which market them as athletic wear, and Lands’ End, where trend-agnostic offerings change little from year to year.

The ’90s are certainly back; if your sunny heart wants a fanny pack or a platform sneaker, you can find them at most department stores. But while ’90s fashion influencers were enamored of the low-rise (we’ll always have Paris), today’s are devoted to the high-rise and the “mom jean.” The contemporary embrace of the high waist — including high-rise bikini bottoms, which have been flying off shelves for several seasons — frankly makes more sense than tying a cardigan around one’s waist each time one sits in order to conceal one’s exposed butt crack. (The author speaks from experience.)

The second life of the tankini is a natural realization of these nostalgia and coverage currents. So it’s simply the rebrand that puzzles. Why are so many retailers resisting the word?

The original tankini was perhaps the most vulnerable swimwear trend that’s taken popular hold. It simultaneously admitted the wearer’s desire for exposure and her reticence to be exposed. That honest conflict is too hard to look at for too long, particularly as the battleground is our bodies. The word “tankini” is liminal; it refuses to override the question, uneasily staking middle ground. A “rash guard,” breezily, means nothing.

By Melissa Batchelor Warnke for Vox.com