1. Noun.  One who initiates.
  2. Noun.  (chemistry) A substance that initiates a chain reaction or polymerization.
  3. Noun.  (computing) A task (in a mainframe computer) that initiates multiple jobs.
  4. Noun.  (medicine) A material whose presence in the body eventually leads to cancer.

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This entry was last updated on RefTopia from its source on 3/20/2012.