Clam up
Meaning
To suddenly stop talking and refuse to speak, often due to shyness, fear, or a desire to keep information secret.
Origin
The phrase 'clam up' vividly depicts the defensive behavior of a bivalve mollusk. When disturbed or threatened, a clam rapidly retracts its soft body and snaps its two shells tightly shut, becoming impenetrable and silent. This natural, protective reflex became a potent metaphor in American English for a person suddenly refusing to speak, sealing off their thoughts and words as firmly as a clam seals its shell. The image captures the sudden, absolute silence and the perceived inability to extract any information, making it a perfect descriptor for someone who becomes uncommunicative.
Examples
- Whenever the police asked about the incident, he would clam up completely and offer no details.
- She tends to clam up when meeting new people, making it difficult for others to get to know her.