Source : Webster's Revised Unabridged Dictionary (1913)

Mugwump \Mug"wump`\, n. [Cf. Algonquin mugquomp a chief.]
   A bolter from the Republican party in the national election
   of 1884; an Independent. [Political Cant, U.S.]

Source : WordNet®

Mugwump
     n 1: someone who bolted from the Republican Party during the U.S.
          presidential election of 1884
     2: a neutral or uncommitted person (especially in politics)
        [syn: {independent}, {fencesitter}]