Wiktionary:Word of the day/2021/November 23

1. (Ancient Greece, historical)
   1. A group of singers and dancers in a theatrical performance or religious festival who commented on the main performance in speech or song.
   2. A song performed by the singers of such a group.
2. (by extension, chiefly British, theater, historical) An actor who reads the prologue and epilogue of a play, and sometimes also acts as a commentator or narrator; also, a portion of a play read by this actor.
3. A group of singers performing together; a choir; specifically, such a group singing together in a musical, an opera, etc., as distinct from the soloists; an ensemble.
4. (by extension) A group of people in a performance who recite together.
5. An instance of singing by a group of people.
6. (figuratively)
   1. A group of people or animals who make sounds together.
   2. The noise or sound made by such a group.
7. (music)
   1. A piece of music, especially one in a larger work such as an opera, written to be sung by a choir in parts (for example, by sopranos, altos, tenors, and basses).
   2. A part of a song which is repeated between verses; a refrain.
   3. The main part of a pop song played after the introduction.
   4. A group of organ pipes or organ stops intended to be played simultaneously; a compound stop; also, the sound made by such pipes or stops.
   5. (often attributively) A feature or setting in electronic music that makes one instrument sound like many.
   6. (Christianity) A simple, often repetitive, song intended to be sung in a group during informal worship.
   7. (jazz) The improvised solo section in a small group performance.

chorus v

1. (transitive)
   1. To sing (a song), express (a sentiment), or recite or say (words) in chorus.
   2. To express concurrence with (something said by another person); to echo.
   3. (rare) To provide (a song) with a chorus or refrain.
2. (intransitive)
   1. To sing the chorus or refrain of a song.
   2. To sing, express, or say in, or as if in, unison.
   3. To echo in unison another person's words.
   4. Of animals: to make cries or sounds together.

For some Christian churches, yesterday was the feast day of Saint Cecilia, the patron saint of musicians.