The tenor recorder is a member of the recorder family. It has the same form as a soprano (or descant) recorder and an alto (or treble) recorder, but it produces a lower sound than either; a still lower sound is produced by the bass recorder.
The tenor recorder, like the soprano recorder, is tuned in C, but an octave lower. Because of its larger size, many tenors have keys to make it easier to play the lowest C, C♯, D, and D♯.
In modern notation, the tenor is written at sounding pitch, unlike most of the other recorder sizes, which (except sometimes the alto) are written an octave lower than they sound.