The term onesie in reference to an adult-sized garment has only emerged in the last couple of years or so, but the word in fact originated as a registered trademark of Gerber Childrenswear, a US company that distributes baby products. Gerber’s trademarked term is Onesies which, analogous to the trademark Babygro in the UK, has been adopted in American English as a generic term for infant bodysuits. The company has defended the trademarked status of the term, opposing its genericized usage and also its adaptation to the singular form. The fact that the term onesie has now become a popular reference on both sides of the Atlantic for an adult version has presumably made its defence as a trademark even more problematic.

The term onesie in reference to an adult-sized garment has only emerged in the last couple of years or so, but the word in fact originated as a registered trademark of Gerber Childrenswear, a US company that distributes baby products. Gerber’s trademarked term is Onesies which, analogous to the trademark Babygro in the UK, has been adopted in American English as a generic term for infant bodysuits. The company has defended the trademarked status of the term, opposing its genericized usage and also its adaptation to the singular form. The fact that the term onesie has now become a popular reference on both sides of the Atlantic for an adult version has presumably made its defence as a trademark even more problematic.