Ithuriel, an angel whom Milton represents as sent by Gabriel to search for Satan in Paradise, who had found entrance by eluding the vigilance of the guard; he was armed with a spear, the touch of which could unmask any disguise, and by means of which he discovered Satan lurking in the garden in the form of a toad.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Ithaca * Itinerary