Trilogy, Tetralogy...

Date: 05/28/2003 at 02:41:14
From: David
Subject: Cardinal/ordinal number systems

If there are ordinal number systems like 1st, 2nd, 3rd, why isn't
there a numbering system for groups like trilogies? I've heard of
quintologies and hexologies but these words don't appear in the
dictionary, (and I've checked many). If a trilogy is possible, why not
a quadrilogy?

In the dictionary a trilogy is defined as a series or group of three. 
But I can't find any terms for a group of four, five, six, seven, etc.
Are there terms for number groups other than three?

Thanks for your time.

Date: 06/04/2003 at 16:10:22
From: Doctor Peterson
Subject: Re: Cardinal/ordinal number systems

Hi, David.

There are several different sets of terms for groups of three, 
depending on what you are counting: "trilogy" for books, "trio" for 
musicians or other people, "triplet" for children or generic groups, 
"triple" for numbers, "triad" for musical notes and so on. Each of 
these types of words can be found for other numbers:

  3  trio     triplet     triple     triad
  4  quartet  quadruplet  quadruple  tetrad
  5  quintet  quintuplet  quintuple  pentad
  ...

As for four books, considering the fact that trilogy comes from Greek 
roots, the proper word would be not "quadrilogy" but "tetralogy"; and 
in fact my dictionary lists that. It does not, however, list 
"pentalogy" for five books.

The following gives one of these possible lists:

   Naming Nine Things
   http://mathforum.org/library/drmath/view/62004.html 

This lists the Latin and Greek prefixes used to make such words:

   Prefixes in Math
   http://mathforum.org/library/drmath/view/57196.html 

- Doctor Peterson, The Math Forum
  http://mathforum.org/dr.math/ 

Date: 06/05/2003 at 12:36:46
From: David
Subject: Thank you (Cardinal/ordinal number systems)

That's perfect. Thank you for this service. It's been very helpful.