Named after Austrian musicologist Ludwig Ritter von Köchel (1800–1877).
- A number assigned to each work composed by Wolfgang Amadeus Mozart.
- Synonym: K
- 2014, Virginia Euwer Wolff, The Mozart Season, Square Fish (→ISBN), page 78:
- Every Mozart piece has a Köchel number. The Fourth Concerto is K. 218, and the highest Köchel number is 626. I was spending my summer with a Köchel number.