quadrology
Used by ignoramuses who can't spell "quadrilogy" or "tetralogy", which are the commonly-accepted terms for a compound work consisting of four distinct works.
I tried to download the Lethal Weapon quadrology, but nobody had any idea what I was talking about.
quadrology
a set of four related items or works, most often used in reference to movies, music, or literature
We had a movie marathon and watched National Lampoon's Vacation quadrology.