baby talk

noun

1. the speech of children learning to talk, marked by syntactic differences from adult speech and by phonetic modifications like lisping, lalling, and the omission and substitution of sounds.
2. a style of speech used by adults in addressing children, pets, or sweethearts, and formed in imitation of the voice and pronunciation of children learning to talk: it is generally characterized in English by the addition of diminutive endings to words, the use of special words and pet names, and the systematic distortion of certain words, as dolly for doll, teensy-weensy for tiny, oo for you, and twain for train.

noun

1. the speech of very young children learning to talk
2. an adult’s imitation of this