Adjective
1. marked by absence of sound;
"a silent house""soundless footsteps on the grass""the night was still"2. failing to speak or communicate etc when expected to;
"the witness remained silent"3. indicated by necessary connotation though not expressed directly;
"gave silent consent""a tacit agreement""the understood provisos of a custody agreement"4. not made to sound;
"the silent `h' at the beginning of `honor'""in French certain letters are often unsounded"5. having a frequency below or above the range of human audibility;
"a silent dog whistle"6. unable to speak because of hereditary deafness