What does "clam up" mean?

To suddenly stop talking To become silent, especially when asked questions.

How do you use "clam up" in a sentence?

He clammed up when the police arrived. She clams up whenever I mention it. Don't clam up on me.

Phrasal Verb BritishAmericanAustralian ★★★★☆ Common informal

Meaning: To suddenly stop talking

突然沉默，闭口不言

Cerrar el pico, quedarse callado

口を閉ざす、黙り込む

입을 다물다, 갑자기 말을 멈추다

To become silent, especially when asked questions.

因紧张或保密而突然沉默。

Quedarse en silencio, a menudo por nerviosismo o para guardar un secreto.

緊張や秘密のために急に黙ること。

특히 질문을 받았을 때 갑자기 침묵하는 것.

Base verb: clam

Particle: up

Separable: No — the verb and particle stay together

He clammed up when the police arrived.
警察一来他就闭口不言了
Se quedó callado cuando llegó la policía
警察が来ると彼は口を閉ざした
경찰이 도착하자 그는 입을 다물었다.
She clams up whenever I mention it.
她一提到这个就不说话了
Se queda muda cada vez que lo menciono
彼女はそのことを言うといつも黙り込む
그녀는 그 얘기만 꺼내면 항상 입을 다문다.
Don't clam up on me.
别这时候不说话啊
No te quedes callado ahora
今になって黙らないで
나한테 입 다물지 마.

Context: silence, avoidance

Tone: defensive

From a clam closing its shell.

Era: Modern

Generation: All ages

Social background: Universal