The Collaborative International Dictionary of English v.0.48:

Oxhead \Ox"head`\, n. [Cf. Hogshead.]
   Literally, the head of an ox (emblem of cuckoldom); hence, a
   dolt; a blockhead.
   [1913 Webster]

         Dost make a mummer of me, oxhead?        --Marston.
   [1913 Webster]