closemouthed (adj.)

• brief
• brusque
• close
• concise
• curt
• dark
• discreet
• dumb
• evasive
• laconic
• mum
• mute
• quiet
• reserved
• reticent
• secret
• secretive
• shifty
• short
• silent
• snug
• speechless
• taciturn
• terse
• tongue-tied
• uncommunicative
• untalkative
• wordless