IPA: /tɛˈtrælədʒi/
KK: /tɛˈtrælədʒi/
A set of four related works, such as plays, operas, or novels, that are connected in theme or story.
The tetralogy of novels explores the lives of four friends over several decades.
Tetralogy → It is formed from "tetra-" (from Greek "tetra", meaning four) and "logia" (from Greek "logia", meaning discourse or study). The word refers to a group of four works, particularly in literature or drama, that are related to each other.
Think of 'tetra-' meaning four, and 'logia' meaning study or discourse — a tetralogy is a study or collection of four related works.