A repertory is a collection of pieces that a performer, group, or theater regularly performs and keeps ready to present. A pianist's repertory might include dozens of memorized pieces, from Bach fugues to Chopin nocturnes, that she can perform at any time. A theater company's repertory consists of all the plays it has staged and can bring back with its current actors.

A magician builds a repertory of tricks they've mastered. A storyteller develops a repertory of tales they can tell at a moment's notice. Symphony orchestras maintain an extensive repertory of classical works, from Beethoven symphonies to modern compositions.

Repertory theater is a special type of theater where a company of actors performs multiple plays in rotation, sometimes switching between different shows from week to week. Instead of running one play for months, they might perform Shakespeare on Monday, a mystery on Wednesday, and a comedy on Friday. The actors need to remember lines and blocking for several plays at once, which requires impressive skill and preparation.

You might also hear the related word repertoire, which means essentially the same thing but is more common in everyday speech.