Definition of Tacet:

part of speech: verb, impersonal

In written music, a term used to indicate when a part is to be silent during a whole movement.

Usage examples:

• A sudden silence, as when the word tacet in an orchestral score hushes to silence bassoons and horns, drums and cymbals, all the instruments that but a moment before were convulsing the air with myriad waves of sound. Herbert Strang in "Round the World in Seven Days".

• This is the same as, 'Qui tacet negat. Mór Jókai in "The Golden Age in Transylvania".