Meaning of four-letter word

four'-let•ter word'

Pronunciation: (fôr'let"ur, fōr'-), [key]
  1. any of a number of short words, usually of four letters, considered offensive or vulgar because of their reference to excrement or sex.
  2. any word, typically of four letters, that represents something forbidden, disliked, or regarded with extreme distaste: In the dieter's vocabulary, “cake” is a four-letter word.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.