system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] The Doctor is said to speak 'Baby'. If Baby is a language, why doesn't the TARDIS translate it like it does with all other languages?
gpt
Two options: He's kidding, or 'Baby' isn't actually a language but he still possesses ability to communicate with infants. 

Going with the latter on the basis of the former being Boring And Therefore Wrong, infants can say things with meaning, but lack the formalized structure of a language which allows others to understand that meaning. The TARDIS specifically only translates language, otherwise incoherent cries of pain and the like would come across as words. The Doctor, however, as one of the most skilled telepaths in a race of extremely powerful telepaths, can make sense of the thoughts behind what the child is attempting to say and translate them into their English equivalent on the fly.