Source : Webster's Revised Unabridged Dictionary (1913)

Initiator \In*i"ti*a`tor\, n. [L.]
   One who initiates.

Source : WordNet®

initiator
     n : a person who initiates a course of action [syn: {instigator}]

Source : Free On-Line Dictionary of Computing

initiator
     
        {SCSI initiator}