(4 syl.). Pictures of grotesque scenes in low life, such as country wakes, penny weddings, and so on. They are so called from the Italian word bamboccio (a cripple), a nickname given to Pieter van Laer, the first Dutch painter of such scenes, distinguished in Rome.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Bambocciades from Infoplease: