Green’s Dictionary of Slang

mugwump n.

[SE mugwump, ‘one who holds more or less aloof from party-politics, professing disinterested and superior views. In 1884, spec. applied to Republicans who refused to support the nominee of their party for president. Also, a person who withdraws his support from any group or organization’ (OED) ]
(orig. US)

1. a person in authority, a self-important person .

[US] in Nation LII 414/3: The secret bulletin [...] has extensively circulated among the Knights of Kadosh and the Most Worshipful Mug-Wumps of the Cabletow [DA].
Great Western 4 July ‘Leader’ n.p.: Then the great mugwump was delivered of a speech which the faithful loudly applauded [F&H].
J.H. Bromley in N.Y. Trib. 16 Feb. n.p.: John A. Logan is the Head Centre, the Hub, the King Pin, the Main Spring, Mogul, and Mugwump of the final plot .
[UK]Belfast News Letter 26 May 5/7: ‘Mugwump’ . . . is synonymous with the New York term ‘big bug,’ or the Washington expression ‘swellhead’ .
St Paul Dly Globe (MO) 30 Dec. 4/4: Webster’s dictionary will admit the words ‘boycott,’ ‘dude’ and ‘mugwump.’ Fancy the Westers [...] making the acquaintance of the dude and mugwump.
[US]F. Harris ‘Gulmore, the Boss’ in Elder Conklin & Other Stories (1895) 174: The building of the branch line South has brought a lot of Irish here – they’re all Democrats – and there’s quite a number of Mugwumps.
[Aus]Truth (Sydney) 4 Mar. 1/5: Are words are cant of thumb-rule, / Where mug-wumps and scum rule.
[US]A.H. Lewis Boss 158: There aint a man in New York who [...] aint makin’ money through a broken law, an’ these mugwumps aint any exception.
[Aus]Sun. Times (Perth) 4 Dec. 1/1: The Mugwump Ministry are reaching out for the insufferable Scotch sabbath [...] Sunday boating, train-riding, park-haunting and cuddling will be prohibited shortly.
[Aus]Sun. Times (Perth) 13 Feb. 2nd sect. 1/4: The latest move of the municipal mugwumps is the application of the ‘move-on’ clause to the [...] seaside.
[UK]J. Buchan Mr Standfast (1930) 495: He would get himself disliked in the popular papers, but all the mugwumps would admire his moral courage.
[US]N.Y. Times 10 May n.p.: The royal red Indian mug-wump, the chief, was copiously red-blooded [DA].
[Aus]E. Curry Hysterical Hist. of Aus. 204: Of course, such erudite little mugwumps as you are all know what Utopia means, don’t you?

2. an obnoxious, foolish person.

[US]Nat. Police Gaz. (NY) 28 Nov. 2/2: A mugwump is [...] every sad-eyed and sheepish looking individual you meet.
[US]M.D. Landon Eli Perkins: Thirty Years of Wit 278: He wasn’t anything. He was – well, he was just a mugwump!
[US]Independent (Honolulu) 13 Jan. 2/2: A is for Armstrong, just so [...] / Some call him a chump / And others a mugwump.
[US]Vanguard Library 31 Mar. 2: How should I know, you half-baked mugwump?
[UK]Marvel 26 June 11: Suppose our judge and his hangman are such pudden-headed idiots as your mugwump of a sergeant?
[UK]Derby Dly Teleg. 15 Feb. 8/3: The biggest ‘mugwump’ of all was the man who forgot his plus-fours.
[UK]E. Cross Tailor and Ansty 101: Am Bostha! you’d search the earth before you would find an equal pack of mugwumps of bladdergashes!
[UK]A. Sinclair My Friend Judas (1963) 22: You moronic mugwump.

3. in attrib. use of sense 2.

[Scot]Falkirk Herald 8 Feb. 2/6: You are deceived by the views which obtain in Wall Street and among New York mugwump pressmen.
[Scot]Dundee Courier 9 Feb. 5/4: Aristocratic nomenclature [...] ‘Guinea-Pig London’, ‘Bumptious Birmingham,’ ‘Mugwump Manchester’ would all look good with a title in front of them.

4. in political terms, one whose vote may go either way and is thus untrustworthy; thus Mugwumpery n., the attitude of such voters; extnded to non-political contexts (see cite 1904).

[US]N.Y. Eve. Post 20 June n.p.: We have yet to see a Blaine organ which speaks of the Independent Republicans otherwise than as Pharisees, hypocrites, dudes, mugwumps, transcendentalists .
[US]Life 6 286/1: [title] An Idyll of Mugwumpery.
[US]F. Francis Jr Saddle and Mocassin 188: I am uncertain what the burro’s politics were; some of the boys asserted that he was a Mugwump.
[US]E. Townsend Chimmie Fadden Explains 81: His Whiskers and Mr. Burton and Mr. Paul used t’ jaw and jaw bout politics and bosses and Mugwumps.
[US]G. Smith is the Constitution Outworn? 263: Mugwumpery " is not a mere mutiny or a craze ; it is a sane, and likely to prove a lasting, revolt of independent patriotism against the autocracy of the " boss.
[US]A.H. Lewis Boss 355: Besides the two regular parties, and the mugwump-independents [...] the laborites would try again.
[Aus]Sydney Sportsman (Surry Hills, NSW) 28 Dec. 1/1: Moral Mugwumpery. The daily press Is now Buttering from a severe.attack of moral mugwumps.
[US]L.A. Herald 5 Jan. 46/2: What is a mugwump? [...] People generally define him as a disgruntled politician.
[Aus]Truth (Perth) 25 June 8/8: A mugwump, Mr Norton, / Are an undecided man, / Who can never make his mind up / On to any settled plan.
[US]M.G. Hayden ‘Terms Of Disparagement’ in DN IV:iii 203: mugwump, political term of disparagement.
[US]Tuscaloosa (AL) News 31 Mar. 4/7: A few moments after Secretary Wallace made his pun, he hastened to add that he himself had been a mugwump [DA].
[US]Wall Street Journal 3 Apr. n.p.: Liberal Republicans called Mugwumps defected to his camp [R].

In derivatives

mugwumping (adj.)

foolish.

[UK]D. Lawley Hustling Hobo 293: Unionism is the craziest darned buiness on earth, and the way it’s carried on in this man’s land makes it a mugwumping business.