Definitions for baby talk
Random House Webster's College Dictionary
the speech of children learning to talk, marked esp. by syntactic simplification and phonetic modifications like omission and substitution of sounds.
a style of speech used by adults in imitation of this, esp. in addressing young children.
Origin of baby talk:
baby talk, babytalk, motherese(noun)
an adult's imitation of the speech of a young child
baby talk, babytalk(noun)
the developing speech of a young child
The form of speech used by adults in talking to very young children.