(A). A child's name for a young chicken, and a mother's word of endearment to her young child. “Biddy” is merely the call of a child, bid-bid-bid-bid to a chicken.
“Do you, sweet Rob? Do you truly, chickabiddy?”—Dickens: Dombey and Son.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894