The Collaborative International Dictionary of English v.0.48:

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.
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         "Graunt mercy, lord, that thank I you," quod she.
                                                  --Chaucer.
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         I thank thee for thine honest care.      --Shak.
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         Weigh the danger with the doubtful bliss,
         And thank yourself if aught should fall amiss.
                                                  --Dryden.
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