i Register
In some senses, bantling is marked as archaic, derogatory, UK. Watch for register when choosing this word.
noun
An infant or young child.
And I even question whether any tender virgin, who was accidentally and unaccountably enriched with a bantling, would save her character at parlour fire-sides and evening tea-parties, by ascribing the phenomenon to a swan, a shower of gold, or a river god.
"You!--half-grown, venison-hunting bantling!..."
A bastard-child.
A brat.