Pickaninny

is a word which was not uncommon when I was a child
and reading books such as Little Black Sambo.
Probably it is now as taboo as Nigger.

Other forms are picaninny or piccaninny or picinniny.
It refers to children of black descent or a racial caricature thereof. 
It may be derived from the Portuguese pequenino 
(an affectionate term derived from pequeno, "little").

Of course, pickaninnies were also cotton-pickers, 
but few were ninnies,

nor indeed asses, nor donkeys - 
a word derived from the Scottish first-name Duncan
which has replaced ass in modern English...