Story highlights "Mugwump" can mean someone undecided in politics or bolters from the Republican party in 1884

The word was used in the Harry Potter books for the head of a wizards' confederation

(CNN) British Foreign Secretary Boris Johnson stepped into the UK election fray Thursday with an editorial describing Labour leader Jeremy Corbyn as a "mutton-headed old mugwump."

Johnson has long been known for his outspoken views and colorful use of the English language. But this very personal attack on Corbyn, in a column for the UK's Sun tabloid newspaper, was the Conservative politician's first direct foray into campaigning for the June 8 snap general election and came after UK political commentators had noted his low profile.

Opposition Labour party leader Jeremy Corbyn speaks in the House of Commons in London last week.

Mugwump?

To save you reaching for the dictionary, Merriam-Webster (which featured mugwump as its word of the day just last November,) gives two definitions: "a bolter from the Republican party in 1884" and "a person who is independent (as in politics) or who remains undecided or neutral."

The dictionary's website also notes that "Mugwump is an anglicized version of a word used by Massachusett Indians to mean 'war leader.' The word was sometimes jestingly applied in early America to someone who was the 'head guy.'"

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