Tasto /(täs"tō̇)/

Tas·to

Tasto

n.
  1. A key or thing touched to produce a tone. (Mus.)

Phrases & Compounds
Tasto solo
single touch; -- in old music, a direction denoting that the notes in the bass over or under which it is written should be performed alone, or with no other chords than unisons and octaves.