Source : Webster's Revised Unabridged Dictionary (1913)

Gooroo \Goo*roo"\, Guru \Gu*ru"\, n. [Hind. gur? a spiritual
   parent or teacher, Skr. guru heavy, noble, venerable,
   teacher. Cf. {Grief}.]
   A spiritual teacher, guide, or confessor amoung the Hindoos.
   --Malcom.