Baby Pajama Pants

pajama
(usually plural) loose-fitting nightclothes worn for sleeping or lounging; have a jacket top and trousers
Pajamas, also spelled pyjamas (see also spelling differences) can refer to several related types of clothing. The original paijama are loose, lightweight trousers fitted with drawstring waistbands and worn in South and West Asia by both sexes.
a pair of loose trousers tied by a drawstring around the waist; worn by men and women in some Asian countries

pants
Trousers
(pant) breathe noisily, as when one is exhausted; "The runners reached the finish line, panting heavily"
Underpants
Rubbish; nonsense
bloomers: underpants worn by women; "she was afraid that her bloomers might have been showing"
(pant) the noise made by a short puff of steam (as from an engine)

baby
The youngest member of a family or group
A young or newly born animal
pamper: treat with excessive indulgence; "grandparents often pamper the children"; "Let's not mollycoddle our students!"
A very young child, esp. one newly or recently born
a very young child (birth to 1 year) who has not yet begun to walk or talk; "the baby began to cry again"; "she held the baby in her arms"; "it sounds simple, but when you have your own baby it is all so different"
the youngest member of a group (not necessarily young); "the baby of the family"; "the baby of the Supreme Court"