moppet

Etymology

From mop (“child, girl”) + -et.

noun

1. (colloquial) A child. Often used lovingly or in an affectionate way.
   They are also very sympathetic, especially Caesar’s orangutan advisor, Maurice (Karin Konoval), who takes a shine to a human moppet (Amiah Miller) he finds hiding in the back of a shack, and the poignant Bad Ape (a scene-stealing Steve Zahn), a mangy chimp who was beaten so often in his zoo-animal days that he came to believe what his handlers were shouting was supposed to be his name. July 7, 2017, Ignatiy Vishnevetsky, “The ambitious War For The Planet Of The Apes ends up surrendering to formula”, in The Onion AV Club
2. (dated) A rag baby; a puppet made of cloth.
3. (dated) A long-haired pet dog.