Opposite words for passion:
composure, antipathy, repugnance, detachedness, patience, reservedness, chastity, insensitivity, stoniness, animosity, dryness, forbearance, averseness, dislike, abhorrence, peace, amiability, nausea, abomination, repulsion, hostility, coldness, collectedness, apathy, insensitiveness, abstinence, woodenness, lenity, distaste, insouciance, disfavor, mildness, taciturnity, enmity, leniency, stoicism, allergy, impassivity, nonchalance, aloofness, disliking, frigidity, long-suffering, revulsion, stiffness, insensibleness, peacefulness, hatred, disinclination, self-control, impassiveness, peaceableness, calmness, chilliness, celibacy, gentleness, coolness, antagonism, reticence, phlegm, charity, self-restraint, frigidness, love, aversion, reserve, indifference, misanthropy, loathing, unfeelingness, hate, rancor, insensibility, disgust, unconcern.
Usage samples:
  1. I shall try to put her in a passion.
    "Mopsa the Fairy", Jean Ingelow.
  2. Besides, there was some hope in the thought that Gomez could not be moved by passion.
    "The Coast of Adventure", Harold Bindloss.
  3. It was in truth a year of great passion and great despair.
    "Confessions of a Young Man", George Moore.
  4. Carse turned, his face white with cold passion.
    "The Affair of the Brains", Anthony Gilmore.