tenor, highest natural male voice. In medieval polyphony, tenor was the name given to the voice that had the cantus firmus, a preexisting melody, often a fragment of plainsong, to which other voices in counterpoint were added. The cantus was arranged in notes of long duration, hence the term tenor, from the Latin tenere, to hold. In about the 12th cent., when this practice arose, the various parts in polyphonic music were roughly equal in range, and it was some centuries later that tenor came to denote a voice of any certain range. The male alto range is termed countertenor. In certain families of instruments the member whose register corresponds to that of the tenor voice is called tenor, e.g., tenor horn and tenor trombone.