What does "twelfth" mean?

Twelfth: Consisting, or being one of, twelve equal parts into which anything is divided.

Additional senses

  1. 2.The quotient of a unit divided by twelve; one of twelve equal parts of one whole.
  2. 3.The next in order after the eleventh.
  3. 4.(Mus.) An interval comprising an octave and a fifth.

Sources