In reply to:

capotasto, noun.
a device attached to a fretted musical instrument,
such as the guitar, for the purpose of raising the
pitch of all the strings at once.

I've heard of these referred to only as "capos"--but never as capotastos. Cool, wwh!

The only listing of the word I could find on Onelook.com was a slightly different spelling: capo tasto with a reference to the Italian as capotasto

I wish Emanuela would look in here and translate. I would think capo might have something to do with the head...