Source : Webster's Revised Unabridged Dictionary (1913)

Behead \Be*head"\, v. t. [imp. & p. p. {Beheaded}; p. pr. & vb.
   n. {Beheading}.] [OE. bihefden, AS. behe['a]fdian; pref. be-
   + he['a]fod head. See {Head}.]
   To sever the head from; to take off the head of.

Source : WordNet®

beheading
     n 1: execution by cutting off the victim's head [syn: {decapitation}]
     2: killing by cutting off the head [syn: {decapitation}]