A "Kern baby" is a term used to refer to a small, chubby or plump baby. While there might not be an abundance of exact synonyms for this word, there are a few alternatives that carry a similar meaning. One such term could be "cherub", which typically describes a round-faced, angelic-looking child. Another option might be "roly-poly", which emphasizes the baby's rounded and plump physique. Additionally, "pudgy" or "chubby" could be used to describe a Kern baby, highlighting their adorable, round appearance. Although not an exact match, these synonyms provide alternatives to convey the idea of a cute and cherubic baby.