(informal)remain silent, especially so as not to reveal a secret(非正式)（尤指為保密）保持沉默，守口如瓶
mum's the word
Say nothing of the secret you know保密：保守你知道的秘密
柯林斯高階英漢雙解學習詞典釋義
N-FAMILY
媽媽
Your mum is your mother.
例句
He misses his mum...他想念他的媽媽。Mum and Dad are coming for lunch...爸爸和媽媽要來吃午飯。
PHRASE
保守秘密;閉口不談
If you keep mum or stay mum about something, you do not tell anyone about it.
例句
He is keeping mum about his feelings on the matter.他閉口不談他對此事的個人感受。
英漢詞典釋義
n.
<口>媽媽
There was always a honeymoon period when Mum started a new job.媽媽每開始一份新工作總會有一陣兒新鮮勁。The cat acted as a surrogate mum to the chicks.這只貓當起了小雞的媽媽來。Your mum will go spare if you don’t go to school!要是你不上學,你媽媽會氣壞的!
adj.
沉默的
I just kept mum when she asked me where Ben was. She’d be furious if she knew.她問我本在哪里,我沒有告訴她。如果她知道了,一定非常生氣。
保持沉默；緘口不言
I just kept mum when she asked me where Ben was. She’d be furious if she knew.她問我本在哪里，我沒有告訴她。如果她知道了，一定非常生氣。Please will everyone keep mum about Saturday. We want to give them a real surprise.請大家對周六的事情保密，我們想給他們一個驚喜。
(用于提醒某人保守秘密或告訴某人自己會保守秘密)不要外傳
‘Nobody must mention this project outside the office. I hope that’s clear.’ ‘We understand, John. Mum’s the word!’“請大家千萬不要在辦公室以外的地方談論這個項目，我希望每個人都明白這一點?！薄凹s翰，放心吧，我們都理解，守口如瓶！”
英英詞典釋義
Noun
1. of China
2. informal terms for a mother
3. secrecy;
"mum's the word"
Adjective
1. failing to speak or communicate etc when expected to;