quiet as a mouse
Also, still as a mouse. Silent, without noise, as in She sneaked into the house, quiet as a mouse, or When he heard the news he was still as a mouse. The first of these similes dates from the mid-1500s, the second from the 1300s.
Words nearby quiet as a mouse
quiddity,
quidnunc,
quiescent,
quiescent tank,
quiet,
quiet as a mouse,
quiet lung,
quiet revolution,
quiet sun,
quieten,
quietism