Antonyms of loyal:
disloyal, unpatriotic, seditious, subversive, rebellious, renegade, treasonous, unfaithful, insurgent, traitorous, faithless, mutinous, recreant, treasonable, capricious, false, untrustworthy, fickle, untrue, wavering, irresponsible, undependable, unreliable, faltering, hesitant, vacillating, dubious, irresolute, shaky, uncertain, apathetic, dispassionate, uninterested, inconstant, perfidious, treacherous.
Examples of usage:
  1. " See you, M'sieu," he whispered; " how loyal are the servants of the North- west Company?"
    "The Maid of the Whispering Hills", Vingie E. Roe.
  2. Then she wished at least to be sure of the sympathy, the friendship of this good loyal man.
    "The Complete Historical Romances of Georg Ebers", Georg Ebers.
  3. Are you that loyal, courageous Marquis de Jarjayes?
    "Marie Antoinette And Her Son", Louise Muhlbach Official.