Source : Webster's Revised Unabridged Dictionary (1913)

Buddhism \Bud"dhism\, n.
   The religion based upon the doctrine originally taught by the
   Hindoo sage Gautama Siddartha, surnamed Buddha, ``the
   awakened or enlightened,'' in the sixth century b. c., and
   adopted as a religion by the greater part of the inhabitants
   of Central and Eastern Asia and the Indian Islands. Buddha's
   teaching is believed to have been atheistic; yet it was
   characterized by elevated humanity and morality. It presents
   release from existence (a beatific enfranchisement,
   Nirv[^a]na) as the greatest good. Buddhists believe in
   transmigration of souls through all phases and forms of life.
   Their number was estimated in 1881 at 470,000,000.

Source : WordNet®

Buddhism
     n 1: a religion represented by the many groups (especially in
          Asia) that profess various forms of the Buddhist
          doctrine and that venerate Buddha
     2: the teaching of Buddha that life is permeated with suffering
        caused by desire, that suffering ceases when desire
        ceases, and that enlightenment obtained through right
        conduct and wisdom and meditation releases one from desire
        and suffering and rebirth