a person who is made to bear the blame for another's mistake; scapegoat.
2.
(formerly) a boy educated along with and taking punishment in place of a young prince or nobleman.
Origin
1640-50
British Dictionary definitions for whipping boy
whipping boy
noun
1.
a person of little importance who is blamed for the errors, incompetence, etc, of others, esp his superiors; scapegoat
Word Origin
C17: originally referring to a boy who was educated with a prince and who received punishment for any faults committed by the prince
Idioms and Phrases with whipping boy
whipping boy
A scapegoat, as in This department's always been the whipping boy when things don't go well. This expression alludes to the former practice of keeping a boy to be whipped in place of a prince who was to be punished. [ Early 1900s ]