A malapropism is the ridiculous misuse of a word, particularly in error as a result of confusing it with another that sounds similar.
The term, malapropism, comes from the name of a self-educated character, Mrs. Malaprop, who appeared in The Rivals, an eighteenth century comedy written by the British writer, Richard Sheridan. Mrs. Malaprop frequently substituted a similar sounding word in place of a word that she had intended to use. In turn, her name, Malaprop, derives from mal à propos, French for inappropriate.
Here are a few examples of malapropisms:
That monster was a pigment of her imagination.
I will support him to the best of my mobility.
We hung on every syllabus she spoke.
It is beyond my apprehension.
He was a man of great statue.
He's a wolf in cheap clothing.
Comparisons are odorous.