tight-lipped
Definitions
Reluctant to speak or give information; reticent.
Keeping one's thoughts or secrets to oneself.
Examples
The witness remained tight-lipped throughout the entire police interrogation.
Management has been tight-lipped about the company's upcoming merger plans.
Synonyms
reticent taciturn reserved secretive close-mouthed uncommunicative laconic
Antonyms
talkative loquacious garrulous chatty voluble communicative forthright