absolute refusal to talk;with one’s mouth sealed ❍ 王魁为人谨小慎微，平素沉默寡言，有时甚至～。Wang Kuei was an overcautious person. He was always reticent and sometimes even refused to talk at all.
三缄其口sān jiān qí kǒu
缄：封闭。在其嘴上加了三道封条。比喻说话非常小心谨慎，或一句话也不肯说。hold one’s peace;with one’s lips sealed, absolute refusal to talk