In an NPR story about the election of Scott Brown to Ted Kennedy’s vacated Senate, a Massachusetts legislator, Jim Vallee, declared:
“He’s not a one-dimensional caricature.”
Caricature does not mean the same thing as character. And it is character that is often characterized (!) as being “one-dimensional.”
Novelists do not want to be accused creating of one-dimensional characters: imaginary people who are entirely good or entirely evil. Real people are rarely one-dimensional. Hitler is said to have liked dogs and classical music. Hannibal Lecter enjoys a nice Chianti. In a novel, a one-dimensional hero who never has an unworthy thought, or a villain who lacks some flicker of humanity, comes across as flat and uninteresting.
The OED offers nineteen definitions for the noun character. The definition that applies in the context of the Vallee quotation is:
The sum of the moral and mental qualities which distinguish an individual . . .
A caricature, on the other hand, is intrinsically one-dimensional, or at least lacking in depth. As an artistic rendering, a caricature exaggerates a person’s most noticeable feature. For example, Obama’s ears, Leno’s chin, Bette Davis’s eyes.
Defined by the OED, a caricature is
An exaggerated or debased likeness, imitation, or copy, naturally or unintentionally ludicrous.
Here’s a quotation in which the word caricature is used correctly:
The joy of learning is as indispensable in study as breathing is in running. Where it is lacking there are no real students, but only poor caricatures of apprentices who, at the end of their apprenticeship, will not even have a trade. –Simone Weil