impassive (adj.)

• aloof
• apathetic
• arctic
• autistic
• backward
• bashful
• blank
• blunt
• bored
• bovine
• callous
• calm
• careless
• catatonic
• chilly
• cloistered
• cold
• cold-blooded
• coldhearted
• collected
• composed
• constrained
• contained
• controlled
• cool
• deadpan
• detached
• discreet
• disinterested
• dispassionate
• distant
• drugged
• dry
• dull
• dwindling
• emotionless
• empty
• even-tempered
• expressionless
• fishy
• forbidding
• frigid
• frosted
• frosty
• frozen
• glassy
• guarded
• halcyon
• hardened
• heartless
• heedless
• hushed
• icy
• immovable
• impersonal
• imperturbable
• inaccessible
• incurious
• indifferent
• inexpressive
• insensible
• insensitive
• insentient
• insouciant
• insusceptible
• introverted
• isolated
• lackadaisical
• listless
• matter-of-fact
• mindless
• modest
• moldering
• nonchalant
• objective
• obtuse
• offish
• pacific
• passionless
• patient
• peaceable
• peaceful
• phlegmatic
• placid
• poker-faced
• quiescent
• quiet
• regardless
• remote
• removed
• reposeful
• repressed
• reserved
• restful
• resting
• restrained
• reticent
• retiring
• secluded
• self-absorbed
• sequestered
• serene
• sheltered
• shrinking
• smooth
• soulless
• spiritless
• standoffish
• steady
• still
• stilly
• stoic
• stoical
• stolid
• stony
• subdued
• suppressed
• taciturn
• tranquil
• unaffectionate
• unagitated
• unapproachable
• uncaring
• unconcerned
• uncongenial
• undemonstrative
• undisturbed
• unemotional
• unexcitable
• unexpansive
• unexpressive
• unfeeling
• unflappable
• unimpassioned
• unimpressionable
• uninquiring
• uninterested
• uninvolved
• unloving
• unmindful
• unmoved
• unperturbed
• unresponsive
• unruffled
• unsusceptible
• unsympathetic
• untouchable
• untroubled
• vacant
• waning
• withdrawn
• wooden