Duff \Duff\, 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.

2. In Australia, to alter the brands on (cattle, horses, etc.); to steal (cattle, etc.), and alter their brands.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Duff \Duff\ (d[u^]f), n. [From OE. dagh. [root]67. See Dough.]

1. Dough or paste. [Prov. Eng.]

--Halliwell.

2. A stiff flour pudding, boiled in a bag; -- a term used especially by seamen; as, plum duff.

Source: Webster's Revised Unabridged Dictionary (1913)