Duff (dŭf), n. [From OE. dagh. √67. See Dough.] 1. Dough or paste. [Prov. Eng.] Halliwell.
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2. A stiff flour pudding, boiled in a bag; -- a term used especially by seamen; as, plum duff.
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Duff (dŭf), v. t. [imp. & p. p. Duffed; p. pr. & vb. n. Duffing.] [Etym. uncertain.] [Colloq. or Slang] 1. To treat or manipulate so as to give a specious appearance to; to fake; hence, to cheat.
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2. In Australia, to alter the brands on (cattle, horses, etc.); to steal (cattle, etc.), and alter their brands.
[Webster 1913 Suppl.]