A "onesie" is a one-piece garment, usually made of soft fabric, that covers the entire body from head to toe. It is often worn as sleepwear or for comfort, especially by babies or young children. Full definition
This adorable organic baby gift set comes with a Blue Skull organic baby onesie with a matching organic infant baby hat in a keepsake box. (organicbabygiftboutique.com)
Wearable - monitor maker Rest Devices showed its Mimo Smart Baby Monitor, a cotton onesie with sensors and a companion gadget that captures sound and helps monitor an infant's breathing, skin temperature, body position and activity level. (cnbc.com)