1 B2 idiomatic informal
To suddenly stop talking and refuse to speak or answer questions, especially due to nervousness, fear, or stubbornness
"Every time I try to ask him what's wrong, he just clams up and leaves the room."
clam up
B2 informal intransitive
To suddenly stop talking and refuse to speak, especially when asked questions
In plain English
To suddenly become very quiet and refuse to say anything, like you've closed your mouth tightly and won't open it
What does "clam up" mean?
2 meanings, ordered from most common to least. Color-coded by CEFR level.
2 B2 idiomatic informal
To refuse to give information to an authority (e.g. police), typically out of fear or a desire to protect others
"The witness clammed up as soon as the detective started asking about the other suspects."
Literal vs figurative
Words literally mean
A clam (shellfish) closes its shell very tightly when threatened — to 'clam up' is to close yourself off like a clam
Actually means
To suddenly become very quiet and refuse to say anything, like you've closed your mouth tightly and won't open it
Usage tip
The image is of a clam (a shellfish) closing its shell tightly — just as a clam cannot be opened easily, a person who has 'clammed up' refuses to be drawn out. Commonly used when someone is questioned by police, parents, or in an interview and refuses to speak. Not used in formal writing.
Words that pair with "clam up"
Natural word combinations native speakers use most often.
suddenly completely questioned interview police nervous
How to conjugate "clam up"
The five tense forms you'll use most often.
Base
clam up
I/you/we/they
3rd person
clams up
he/she/it
Past simple
clamed up
yesterday
Past participle
clamed up
have + pp
-ing form
claming up
continuous
Hear "clam up" in the wild
Listen to native speakers using "clam up" in real YouTube videos — click a clip to watch it on Looplines.
Keep exploring
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