Source : Webster's Revised Unabridged Dictionary (1913)

Caution \Cau"tion\ v. t. [imp. & p. p. {Cautioned}; p. pr. & vb.
   n. {Cautioning}.]
   To give notice of danger to; to warn; to exhort [one] to take
   heed.

         You cautioned me against their charms.   --Swift.