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Mother Idioms:To keep Mum and Mum’s the word

Updated: Mar 8, 2021


Mother Vocabulary


'To keep Mum' and 'Mum's the word' are English sayings often used in conversation. If you are learning English as a foreign language, it is useful to understand how some sayings or phrases are used and (most importantly) what they mean.

Mother Vocabulary

Can you think of alternative words for the word mother?

Alternative words for mother include:

  • Mum

  • Mummy

  • Mam

  • Mama

  • Ma

  • Mamma

Do you know what the following phrase means?

To keep Mum

Here is the phrase in a sentence:



I won't tell anyone; I'll keep Mum.

Here is a definition:

I’ll keep Mum = To keep something a secret.

Do you know what the following phrase means?

Mum's the word!

The phrases above are all idioms.


What is an idiom?

An idiom is a figurative expression or saying; it has an established meaning that isn’t directly linked to the individual words.



Here is the idiom in a sentence:

-If I tell you what happened last night will you promise not to tell anyone?

-I promise. Mum’s the word!

Here is a definition:


Definition of Mum's the word = to remain silent; to keep something a secret

Here are some more idioms:

(To have) the mother of all something

I have the mother of all migraines.

I have the mother of all migraines. = An extreme example of something

Mummy’s boy!

Will you invite your wife to my birthday party? I’m not sure. I need to check with my Mum first. -You’re such a mummy’s boy!

A mummy’s boy! = A man or boy whose mother has too much influence on him

Shall I be mother/mum?


This dinner looks lovely? Who’s going to serve?


Shall I be mother, shall I serve?

Shall I be mother /mum? = A humorous way to ask if the speaker should serve food or drink; mostly linked with pouring tea

Can you guess the meaning of this idiom?