- silent沉默的。
短语
keep mum
- informal remain silent, especially so as not to reveal a secret〈非正式〉（尤指为保密）保持沉默, 守口如瓶：
he was keeping mum about a possible move to West Ham.
他对可能转会西哈姆（联队）一事保持沉默。
mum's the word
- informal (as a request or warning) say nothing; don't reveal a secret〈非正式〉［用作要求或警告］别声张; 不要泄密。
词源
late Middle English: imitative of a sound made with closed lips.
mummed, mumming
no obj. act in a traditional masked mime or a mummers' play在传统假面哑剧中扮演（角色）; 在英格兰民俗剧中扮演（角色）。
词源
late Middle English: compare with MUM2 and Middle Low German mummen.