Onesie or onesize is American English for a boysuit for infants designed to conceal a diaper when worn. It is also called a creeper, diaper shirt or snapsuit. The British English equivalent is babygro. Onesie is a genericized trademark registered to Gerber Childrenswear, Inc., which continues to defend its trademark. Babygro is also a trademark brand, invented in the U.S. in the 1950s by Walter Artzt.