Noun
any of several short English words (often having 4 letters) generally regarded as obscene or offensive
Source: WordNetLife is a four-letter word. Lenny Bruce
The thing is, acoustic could be like a four-letter word to a lot of kids. Billie Joe Armstrong
Censorship feeds the dirty mind more than the four-letter word itself. Dick Cavett
Hope is the most important four-letter word in the language. Ed Markey
Now, look, baby, 'Union' is spelled with 5 letters. It is not a four-letter word. Dorothy Parker
You know you're getting old when a four-letter word for something pleasurable two people can do in bed together is R-E-A-D. Denis Norden