Source : Webster's Revised Unabridged Dictionary (1913)

Thank \Thank\, v. t. [imp. & p. p. {Thanked}; p. pr. & vb. n.
   {Thanking}.] [AS. [thorn]ancian. See {Thank}, n.]
   To express gratitude to (anyone) for a favor; to make
   acknowledgments to (anyone) for kindness bestowed; -- used
   also ironically for blame.

         ``Graunt mercy, lord, that thank I you,'' quod she.
                                                  --Chaucer.

         I thank thee for thine honest care.      --Shak.

         Weigh the danger with the doubtful bliss, And thank
         yourself if aught should fall amiss.     --Dryden.