From the Collection:

NMHM/DCA 2010.13.1

Infant’s sunsuit or daysuit. This is a one piece garment with short sleeves, mother of pearl buttons and a scalloped collar. The outfit was worn by the donor on his first birthday, July 20th,1940.
A sunsuit is an old-fashioned term for a child’s one-or-two piece suit of clothes usually consisting of shorts and sleeveless top that was worn in sunny weather but could also be used as a swimsuit. Sunsuits were usually clothing worn by toddler boys, as is the case with this outfit.
NMHM/DCA 2010.13.1