Mandolin players use "tremolo" to refer to the rapid reiteration of a
sustained note by flicking the pick back and forth.  This at least is
consistent with the violinists' usage,  which is not surprising since
the two instruments are tuned the same and often borrow each other's
tunes.

Organ stops are usually spelled "Tremulant."  While it's true that most
pipe organs achieve tremulant by bleeding air out of the main bellows,
the oscillating valve is usually at the end of a long wind trunk which
develops a reaction wave (much like a reed pipe), whose positive
pressure peaks probably raise the wind pressure (and hence pitch) as
much as it gets lowered during the negative peaks.

Based on one horrible experience, I would advise against exposing
anyone to your Violano Virtuoso's playing without the vibrato in
operation :-)

--Mike Knudsen