tightlipped

Từ điển WordNet v3.1 - WordNet Dictionary

adjective

inclined to secrecy or reticence about divulging information
- although they knew her whereabouts her friends kept close about it
• Syn:
close, closelipped, closemouthed, secretive
• Similar to:
uncommunicative, incommunicative
• Derivationally related forms:
secretiveness (for: secretive), secrete (for: secretive), closeness (for: close)