List of impassive synonyms and impassive related words.
Olympian, affectless, aloof, anesthetized, apathetic, arctic, at rest, autistic, backward, bashful, blank, blunt, bored, bovine, callous, calm, careless, catatonic, chill, chilled, chilly, cloistered, cold, cold as charity, cold-blooded, coldhearted, collected, composed, constrained, contained, controlled, cool, deadpan, detached, discreet, disinterested, dispassionate, distant, drugged, dry, dull, dwindling, ebbing, emotionally dead, emotionless, empty, even-tempered, even-tenored, expressionless, fishy, forbidding, frigid, frosted, frosty, frozen, glassy, guarded, halcyon, hardened, heartless, heedless, hushed, icy, immovable, impassible, impersonal, imperturbable, inaccessible, incurious, indifferent, indurated, inexcitable, inexpressive, inirritable, insensible, insensitive, insentient, insouciant, insusceptible, introverted, isolated, lackadaisical, listless, matter-of-fact, mindless, modest, moldering, nonchalant, nonemotional, objective, obtuse, offish, out of touch, pacific, passionless, patient, peaceable, peaceful, phlegmatic, placid, poker-faced, quiescent, quiet, regardless, remote, removed, reposeful, reposing, repressed, reserved, restful, resting, restrained, reticent, retiring, secluded, self-absorbed, sequestered, sequestrated, serene, sheltered, shrinking, smooth, soulless, spiritless, standoff, standoffish, steady, still, still as death, stillish, stilly, stoic, stoical, stolid, stony, subdued, subsiding, suppressed, taciturn, tranquil, unaffable, unaffectionate, unagitated, unapproachable, uncaring, unconcerned, uncongenial, undemonstrative, undisturbable, undisturbed, unemotional, unexcitable, unexpansive, unexpressive, unfeeling, unflappable, ungenial, unimpassioned, unimpressible, unimpressionable, uninquiring, uninterested, uninvolved, unirritable, unloving, unmindful, unmoved, unnervous, unpassionate, unperturbed, unresponding, unresponsive, unruffled, unstirring, unsusceptible, unsympathetic, untouchable, untroubled, vacant, waning, withdrawn, wooden