(n.) The state or quality of being inexpressive.

anesthesia autism catatonia chill chilliness cold blood cold heart coldheartedness coldness coolness deadpan dispassion dispassionateness dullness emotional deadness emotionlessness expressionlessness frigidity frostiness heartlessness iciness immovability impassibility impassiveness impassivity inexcitability inexpressiveness lack of affect lack of feeling lack of touch objectivity obtuseness passionlessness poker face self-absorption soullessness spiritlessness straight face unemotionalism unexcitability unexpressiveness unfeeling unfeelingness unimpressibility unimpressionableness unpassionateness unresponsiveness unsusceptibility unsympatheticness untouchability withdrawal