Opposite words for appear:
retire, die, discontinue, go, be certain, clock, evaporate, vanish, be the fact, finish, quit, withdraw, perish, terminate, _or_ true, cease, end, check out, evanesce, be, pass away, leave, expire, vamoose, conclude, desist, melt, real, depart, dissolve, fade, flee, disappear, clear, exist, halt, stop, go away.
Usage samples:
  1. However incredible this may appear, it is a fact.
    "Cattle and Cattle-breeders", William M'Combie.
  2. He did not appear to care.
    "Black Rock", Ralph Connor.
  3. But you do not appear so very dreadful; though at present you are truly not at your best.
    "The Puppet Crown", Harold MacGrath.
  4. He was the first to appear at the landing.
    "A Lieutenant at Eighteen", Oliver Optic.