reticence (n.)

• aloofness
• backwardness
• bashfulness
• blankness
• chilliness
• coldness
• constraint
• coolness
• detachment
• discreetness
• discretion
• distance
• frigidity
• frostiness
• iciness
• impassiveness
• impassivity
• inaccessibility
• introversion
• modesty
• remoteness
• repression
• reserve
• restraint
• retirement
• standoffishness
• subduedness
• suppression
• unapproachability
• uncongeniality
• withdrawal
• withdrawnness