Some people call it high fashion. Some call it faux-athletic. A lot of people just call it comfy. Whatever.

Merriam-Webster will simply call it “athleisure.”

Starting with its next update in 2016, Merriam-Webster will include the term “athleisure” in its dictionary, covering all those stretchy yoga pants, the tighter-than-tight workout shorts and all the abs-baring tops and clean-lined cover-ups that pair oh-so-nicely with them. The official definition, M-W’s Emily Brewster told the New York Times: “casual clothing designed to be worn both for exercising and for general use.”

Loose, plastic-y sweatpants, clunky sneakers and four-pound cotton hoodies, this is not. Think Gisele, not George Constanza.

“Athleisure” is simply the latest step in a trend that has been around longer, even, than Seinfeld’s Costanza, though it only recently has truly taken off. According to Morgan Stanley, in the past seven years, sales of athletic footwear — sneakers, mainly — and sports apparel has risen 42 percent worldwide. Some $270 billion is spent on it every year.

We’ve seen it from China to Chicago and everywhere in between, from the regular players in the game — names like Under Armour, Nike and Adidas — to more high-end players. Tory Burch has an entire division called Tory Sport. Designer Derek Lam has his own line and has also collaborated with running giant New Balance on a new sneaker.

Where some might decry the trend as the death of fashion and responsibility — “You know the message you’re sending out to the world with these sweatpants?” Seinfeld famously told George. “You’re telling the world, ‘I give up.’” — others see it as a way to incorporate an increasingly healthy lifestyle into everyday wear.

From the Morgan Stanley report:

“The generational and societal shift toward less formal fashion styles over the past few decades hasn’t hurt. Wearing sneakers and jeans to work was once frowned upon, but many professionals now arrive at the office in flashy, multihued trainers and exercise gear …”

Being trendy doesn’t come cheaply. Lam has a pair of “Downtown Leather Joggers” — definitely more “leisure” than “ath” — that goes for $398. A “Performance Legging” from Tory Burch, made of nylon and spandex, sells for $125. Nike has a fancy pair of yoga-type pants that cost $150. Under Armour pitches a pair of running pants for $179.99.

Still, the trend is a trend for a reason: People like the look and the feel of athleisure, as the sales numbers show. And if athleisure isn’t considered as dressed-up as a pair of nice flat-fronts or a sundress in the summer … well, it’s easily as comfortable. At least to a lot of people.

Where the athletic and fashion worlds take us from here, no one knows. Is it OK to actually work out in a $200+ outfit, get all sweaty, then head out to the grocery store (which is kind of the idea, wouldn't you think, of mashing up the words "athletic" and "leisure")? Are those too-tight workout pants really appropriate on a Casual Friday? At the movies? At a dinner at a place with cloth napkins?

Are all those swishy-slick plastic-y sweatpants in your closet really destined for the giveaway box?

We’ll find out soon enough. In the meantime, grab a napkin. You don’t want to spill that lunch on your expensive athleisure.