A malapropism is the use of an incorrect word sounding similar to the word a person originally wished to use. The word malapropism has been derived from English Literature. The famous playwright, Sheridan in his play The Rivals in 1775 introduced a character known as Mrs. Malaprop who would use incorrect words that sounded similar to the word she originally wished to use. The result was a hysterical comedy.

The name is derived from the French mal à propos, which means inappropriate (we also have the word malapropos in English) Here are some classic examples of her malapropisms.

•  “…promise to forget this fellow – to illiterate him, I say, quite from your memory.”
     [obliterate]
   

• “O, he will dissolve my mystery!”
     [resolve]
   
• “He is the very pine-apple of politeness!”
     [pinnacle]
   
• “I have since laid Sir Anthony’s preposition before her;”
     [proposition]
   
• “Oh! it gives me the hydrostatics to such a degree.”
     [hysterics]
   
• “I hope you will represent her to the captain as an object not altogether illegible.”
     [eligible]
   
• “…she might reprehend the true meaning of what she is saying.”
     [comprehend]
   
• “…she’s as headstrong as an allegory on the banks of Nile.”
     [alligator]
   
• “I am sorry to say, Sir Anthony, that my affluence over my niece is very small.”
     [influence]
   
• “Why, murder’s the matter! slaughter’s the matter! killing’s the matter! – but he can tell you the perpendiculars.”
     [particulars]
   
• “Nay, no delusions to the past – Lydia is convinced;”
     [allusions]
   
• “…behold, this very day, I have interceded another letter from the fellow;”
     [intercepted]
   
• “I thought she had persisted from corresponding with him;”
     [desisted]
   
• “His physiognomy so grammatical!”
     [phraseology]
   
• “I am sure I have done everything in my power since I exploded the affair;”
     [exposed]
   
• “I am sorry to say, she seems resolved to decline every particle that I enjoin her.”
     [article]
   
• “…if ever you betray what you are entrusted with… you forfeit my malevolence for ever…”
     [benevolence]
   
• “Your being Sir Anthony’s son, captain, would itself be a sufficient accommodation;”
     [recommendation]
   
• “Sure, if I reprehend any thing in this world it is the use of my oracular tongue, and a nice derangement of epitaphs!”
     [apprehend, vernacular, arrangement, epithets]

Source: http://www.fun-with-words.com/mala_malapropisms.html