Definition of onesie in US English:



North American
  • An infant's one-piece close-fitting lightweight garment, usually having sleeves but leaving the legs uncovered and fastening with snaps at the crotch.

    • ‘We had stacks of onesies we'd bought on sale at Baby Gap.’
    • ‘I'm sorry that I dressed you in that onesie that was too small but was still so cute that I wanted you to wear it at least one more time.’
    • ‘By the time they bring their new little family member home, they've taken classes, read a library's worth of books, and bought enough onesies to fill an entire dresser.’
    • ‘These days you can buy your baby daughter a BORN TO SHOP onesie with little pink purses on it.’
    • ‘I find the t-shirts better than onesies, especially for diaper-changing purposes.’
    • ‘One vendor was even selling a baby's pink onesie emblazoned with the New York Police Department logo.’
    • ‘Little Amy was crawling around the floor in a "Daddy's Girl" onesie.’
    • ‘My baby is 2 weeks old, and because she was 2 weeks late and nearly 10lbs, she isn't fitting into the smaller onesies very well.’
    • ‘I've decided that "experiments with gravity" would be an excellent phrase to print on a baby onesie and toddler t-shirt.’
    • ‘Both stores are also good sources for flannel receiving blankets, pajamas, onesies, and other items that you'll want to buy in bulk.’
    • ‘Do you experience a tingling sense of well-being when you know exactly where the 3-6 month old onesies are in your nursery?’
    • ‘Onesies are very practical clothing for babies to wear.’
    • ‘Her baby brother loved both servings so much that he smeared them all over his face, his onesie, the kitchen floor, and the couch.’
    • ‘Organic cotton is very important for the baby clothing market and the onesie was an easy fit with the youth and baby tees that we already offered.’
    • ‘As you can tell from his onesie, I exclusively breastfeed.’
    • ‘The onesies, in sets of three, will be decorated with a peace symbol, a heart, and a happy face: peace, love, and happiness.’
    • ‘Putting away all the blankets and baby socks and teeny tiny onesies made everything seem so real.’
    • ‘One of the photos in the slideshow was of him as a baby, sporting a onesie with Mickey Mouse on the front.’
    • ‘She gave me tips on creating a full layette and showed me some darling booties and onesies.’
    • ‘She handed me a yellow Carter's onesie with a soft yellow duck on the chest.’


1980s: from Onesies, a proprietary name for a garment of this type, based on one + -sy.