silent
     adj 1: marked by absence of sound; "a silent house"; "soundless
            footsteps on the grass"; "the night was still" [syn: {soundless},
             {still}]
     2: failing to speak or communicate etc when expected to; "the
        witness remained silent" [syn: {mum}]
     3: indicated by necessary connotation though not expressed
        directly; "gave silent consent"; "a tacit agreement"; "the
        understood provisos of a custody agreement" [syn: {implied},
         {tacit}, {understood}]
     4: not made to sound; "the silent `h' at the beginning of
        `honor'"; "in French certain letters are often unsounded"
        [syn: {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 [syn: {dumb},
         {mute}]
Source: WordNet® 2.0