"3" is to "trilogy" what "2" is to ". . ."

Anybody?

Duology.

sequel?

Also known as dilogy.

“Duology” is probably the more correct term. “Dilogy” has a different, distinct meaning, as “a statement that is ambiguous; something that could mean one of two things.” So to avoid confusion I’d suggest “duology,” which has no other definition I can find except precisely what lissener is asking for.

Pair

duology

(doesn’t seem to exist much outside Wikipedia, though)

Trilogy seems to be special, here. What about all the other numbers?

For every “Lord of the Rings Trilogy”, we have plenty of “Oz books” and “Lethal Weapon Movies”. So I’d say that’s your answer. 3? It is a trilogy. Any other number and they’re just books, or movies, or whatever the relevant plural is.

“pair”

“3” describes the number of elements in “trilogy”. “2” describes the number of elements in “pair”. There doesn’t seem to be requirement that “trilogy” and the mystery word have to be related to each other beyond their relation to the numbers “2” and “3”.

Post above should read “any requirement”.

There’s also Diptych.

I think usually we just call them “series” after three.

While duology, pentalogy, heptalogy and so on are all valid words, seen here at reference.com they’re really not used a lot.

That’s specific to art though.

Yes indeed. Or ‘follow-up’.

Using what others have said, I think the sequence goes:

original
sequel
trilogy
series

4 is tetralogy
5 is pentalogy
6 is hexalogy
7 is heptalogy

etc, following the greek numeration.

Damn, I was hoping it was a biology.

The way televison promotion departments talk these days, I’m tempted to say “Two is to miniseries”. :rolleyes: Whatever happend to “two-part”?

But doesn’t “sequel” refer to the second book itself, and not the two-book series as a whole?

Actually, four is “inaccurately named trilogy” and five is “increasingly inaccurately named trilogy.”

That is only in Douglas Adams *Speak * however.

For what it’s worth, strictly speaking The Lord of the Rings should not be referred to as a trilogy. A trilogy is a series consisting of three novels. The Lord of the Rings is a single novel that is frequently published in three volumes. It wasn’t planned as a three-volume work when it was written. If you’ll check your copies you’ll see that it consists of six parts (and some appendices), and each of the three volumes it’s frequently published as contains two of those parts. When Tolkien gave the manuscript to his publisher, he said, “Hmm, this looks like three volumes worth of material. We’ll publish it in three volumes with six months between the publication of each volume.” Tolkien objected, but the publisher said that he was probably going to lose money on the book anyway, so Tolkien should be happy with even getting it published. The titles of the three volumes were decided by Tolkien and the publisher just before the publication.