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flat character vs. round character

flat character

[flat kar-ik-ter] / ˈflæt ˈkær ɪk tər /

noun

an easily recognized character type in fiction who may not be fully delineated but is useful in carrying out some narrative purpose of the author.

round character

[round kar-ik-ter] / ˈraʊnd ˌkær ɪk tər /

a character in fiction whose personality, background, motives, and other features are fully delineated by the author.