Babygrow
A babygrow, babygro, sleepsuit or sleep suit in British English is a one-piece item of baby clothing with long sleeves and legs used for sleep and everyday wear. The feet are often are enclosed, but it may be footless. This terminology is common in the United Kingdom, where the trademark is not registered. In the United States where the trademark is registered, the name is uncommon as other manufacturers of the item use other terms. Instead, the terms sleeper or sleep and play are more common in American English. They are typically made of cotton. If it is made of fleece, it is considered a blanket sleeper. They also may be referred to simply as pajamas or one-piece, or footie pajamas or footed one-piece in American English if it has feet. Typically they are closed with snaps, although zippers are also common. If closed with a zipper, they may be referred to as zipper pajamas, zip up pajamas, or simply zip pajamas.
Onesie (noun)
A one-piece garment for an infant or small child, generally worn over a diaper.
Onesie (noun)
One-piece adult loungewear jumpsuit.
Onesie (noun)
One-piece fashionable streetwear worn mostly by teenagers.
Onesie (noun)
a loose-fitting one-piece leisure garment covering the torso and legs
“I’d had a bath and was in my onesie ready to settle down for yet another reality TV marathon”
Onesie (noun)
a one-piece close-fitting lightweight garment worn by a young child, usually having sleeves but leaving the legs uncovered and fastening with press studs at the crotch.