onesie

American  

[wuhn-zee] / ˈwʌn zi /

noun

• onesies
  plural

1. a one-piece leisure or sleeping garment for an adult, usually combining a long-sleeved top with long pants.

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Trademark.

1. Onesies, a brand name for one-piece garments for infants, the lower portion resembling briefs and having snaps across the crotch for convenience in diapering. Although a trademarked term, it is often spelled as lowercase onesie, referring to a single garment.

onesie British  

/ ˈwʌnzɪ /

noun

1. a one-piece garment combining a top with trousers, worn by adults as leisurewear

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Usage

What else does onesie mean? A onesie is a one-piece item of loungewear or sleepwear. Traditionally, onesies are worn by babies, but they exploded into adult novelty fashion in the 2010s. How is onesie pronounced?[wuhn-zee]

Other Word Forms

Noun Inflected Forms

• onesies
  plural

Etymology

Origin of onesie

First recorded in 1980–85; originally a trademark

Example Sentences

See Examples For:

onesie onesies

My mother-in-law wasn’t one for raunch; she probably just thought the onesie was silly and cute.

From Salon ● Jun. 4, 2026

An omen among omens: Mid-dog-walk that day, I spot a onesie that reads “Milk Drunk” and shudder at the impulse to recruit our newborns into low-key bacchanalia.

From Slate ● May 10, 2026

The 66-pound robot wears a sweater-like onesie, because nothing says “I’m harmless” like cozy knitwear.

From The Wall Street Journal ● Oct. 28, 2025

The boy was last seen wearing a black onesie, authorities said.

From Los Angeles Times ● Aug. 19, 2025

They’d met at Princeton as undergraduates, and Brian had pictures of himself as a baby in a Princeton onesie.

From "Little Fires Everywhere" by Celeste Ng

There’s a certain irony in the famously feuding Gallagher brothers selling clothing for the whole family, including Oasis onesies for babies.

From Los Angeles Times ● Aug. 21, 2025

When guests arrived, Broussard opened gifts — onesies and diapers and bows — while Crain kept closing her eyes.

From Salon ● Nov. 1, 2024

Others purchased $25 toddler onesies with “You talkin’ to me?”

From New York Times ● Jun. 18, 2024

Online shops and local vendors have put together a full array of creative, limited-edition merchandise: earrings, baby onesies, ornaments, games, banners and more.

From Seattle Times ● Mar. 15, 2024

“Uncle Greg has all the HD swag you can imagine. Including a pack of onesies and a tiny leather jacket.”

From "The Season of Styx Malone" by Kekla Magoon