Source : Webster's Revised Unabridged Dictionary (1913)

Tun \Tun\, v. i. [imp. & p. p. {Tunned}; p. pr. & vb. n.
   {Tunning}.]
   To put into tuns, or casks. --Boyle.

Source : WordNet®

tun
     n : a large cask especially one holding a volume equivalent to 2
         butts or 252 gals
     [also: {tunning}, {tunned}]

tunning
     See {tun}