What does m. v. mean?

[miker]

In Brahms rhapsody in B minor.

[motet]

mezza voce, "half voice." It may refer to using the soft pedal here.

[David Ward]

And note that mezza voce does not equate with mf. For a singer ‘half voice’ is really rather quiet and without fully projected tone, indeed sometimes almost tonelessly. One has to create/imagine its instrumental equivalent according to context (as with sotto voce ‘under the voice’). There were queries when Beethoven used sotto voce in some orchestral music, but it is now common enough in both musical and non-musical contexts.

[miker]

Thanks, guys! Always learning!