Meaning
To stop talking or refuse to speak, especially to avoid giving information, answering questions or incriminating someone. Informal in register and standard in both American and British usage, particularly for contexts of interviews, interrogations and gossip. Informal; implies deliberate withholding of information rather than mere shyness. Regional use: American English origin; now General English.
Origin
American; Etymonline dates the phrasal verb to 1916. The image is of a bivalve snapping its two shells tightly shut, and it is older than the idiom in the very name of the animal: the mollusc's name, recorded from about 1500 in Scottish use, comes through Middle English clam, pincers or clamp, from Old English clamm, a bond or grip, so the shellfish was literally named for how tightly it closes. Etymonline also records clam used as a silence-demanding interjection in the mid-fourteenth century, which suggests the association of clams with reticence long predates the verb. American Heritage labels the phrase informal, defines it as to refuse to talk, and separately records the noun clam for a close-mouthed person.
Research Sources
References used to check this entry’s meaning, history, or documented forms.
Variants
- clam up on someone
- clammed up
- clamming up
- suddenly clammed up
Usage Examples
- The witness clammed up as soon as the defence lawyer mentioned the ledger.
- Teenagers tend to clam up when their parents ask too many questions about their friends.
- He was cheerful about everything until I brought up the loan, and then he clammed up completely.