The Collaborative International Dictionary of English v.0.48:

Hindooism \Hin"doo*ism\, Hinduism \Hin"du*ism\, n.
   The religious doctrines and rites of the Hindus; Brahmanism.
   Hindoostani
   Hindoostanee

The Collaborative International Dictionary of English v.0.48:

Hinduism \Hinduism\ n.
   1. the dominant religion of India; characterized by a caste
      system anud belief in reincarnation.

   Syn: Hindooism.
        [WordNet 1.5]

   2. a complex of beliefs and values and customs including
      worship of many gods, especially the Trimurti composed of
      Brahma the Creator; Vishnu the preserver; and Shiva the
      destroyer.

   Syn: Hindooism.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Hinduism
    n 1: the religion of most people in India, Bangladesh, Sri
         Lanka, and Nepal [syn: Hinduism, Hindooism]
    2: a body of religious and philosophical beliefs and cultural
       practices native to India and based on a caste system; it is
       characterized by a belief in reincarnation, by a belief in a
       supreme being of many forms and natures, by the view that
       opposing theories are aspects of one eternal truth, and by a
       desire for liberation from earthly evils [syn: Hinduism,
       Hindooism]