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

As a parent, you wouldn’t want your child to be stuck forever wearing a onesie and drinking from a sippy cup.

From The Wall Street Journal ● Jan. 1, 2026

Dodgers were undefeated when my 6 month old wore a Dodgers onesie, until game 1 of the World Series.

From Los Angeles Times ● Oct. 28, 2025

Ivy laid Aaron down on the changing pad on top of the dresser and wiggled one of his arms out of his onesie.

From "Ivy Aberdeen’s Letter to the World" by Ashley Herring Blake

Fans purchase Rocket Lab-branded shirts, jackets, model rockets and even baby onesies.

From MarketWatch ● Jun. 10, 2026

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

Trainee teacher Laurie Schram says she and her daughter depend on onesies and electric blankets to manage.

From BBC ● Nov. 15, 2023

“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