— blank
— close
— closelipped
— closemouthed
— deadpan
— expressionless
— impassive
— inarticulate
— incommunicado
— inexpressive
— mum
— out of touch
— poker-faced
— secretive
— silent
— straight-faced
— taciturn
— tightlipped
— unarticulate
— unchangeable
— uncomfortable
— uncommon
— uncommonly
— uncomplicated
— uncompromising
— unconcern
— unconcerned
— unconfined
— unconnected
— unconquerable
— unconscionable
— unconscious
— unconsecrated
— unconstrained
— unconstraint
— uncontaminated
— uncontrollable
— unconvincing
— uneconomical
— unexpressive
— unpronounceable
— unutterable
— vacuous