According to thedailygreen.com, the American Dialect Society named the word "flexitarian" the "most useful word of the year" in 2003. The word is defined as a vegetarian who occasionally eats meat.
The reason I found the word so interesting has to do with the way it was formed.
Considering that the word "vegetarian", according to the Online Etymology Dictionary, is an irregular formation from vegetable (n.) + -arian, as in agrarian, etc. , a first instinct might be to wonder why the word "flexitarian" wouldn't have just been "flexarian" or "flexibarian.
Consider the following list of words that have been formed with the "-arian" suffix: