A series of four related dramatic, operatic, or literary works. (noun)
Medicine A complex of four symptoms. (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "tetralogy" in a sentence
"It's very tempting to think and will surely be quite an orgasmic? event, but alas it's only a dream. tetralogy tetralogy*"
"I can imagine someone saying that the New Sun tetralogy is not to his taste, or that some events in the books were unclear at first reading, but you have cut yourself from some of the finest writing in the English language, certainly the finest in science fiction, if you dismiss this wonder as crap."
"Peter Gruber, MD: So it was described as a tetralogy, or four basic problems."