malapropism

"i already made like affinity of those at scout camp." (i.e. an infinity) — Napoleon Dynamite. malapropism means the word used sounds similar to the word that was apparently meant or intended. using "obtuse" (wide or dull) instead of "acute" (narrow or sharp) is not a malapropism; using "obtuse" (stupid or slow-witted) when one means "abstruse" (esoteric or difficult to understand) would be.