What is the meaning of Onesie?

Name given to a number of one-piece attires

  1. A one-piece garment for an infant or small child, generally worn over a diaper.
  1. One-piece adult loungewear jumpsuit.
  2. One-piece fashionable streetwear worn mostly by teenagers.

A one-piece garment for an infant or small child, generally worn over a diaper.

One-piece adult loungewear jumpsuit.

One-piece fashionable streetwear worn mostly by teenagers.

Source: wiktionary.org