Onesie (jumpsuit)

A onesie (/ˈwʌnzi/) is a type of loose-fitting casual jumpsuit in adult sizes made of knit cotton (as used in sweatshirts), fleece, or chenille.

In 2008, when casual jumpsuits became increasingly popular, the press started discrediting them as "adult onesies,"[3][4] and the name seems to have eroded to a generic word, dropping the final "S" in the process.

A type of onesie known as kigurumi (着ぐるみ), or 'cosplay pajamas', emerged as Japanese street fashion and spread outside Japan in 2009.

They became popular worldwide, in particular following a viral video of Miley Cyrus twerking while wearing a unicorn kigurumi.

[5] Historically, the term kigurumi has been used in Japan to refer to the use of full-body mascot or masked outfits in performances and costume play, predating their use as pajamas.