Boris Johnson called Jeremy Corbyn a mugwump - but what is it? #mugwump
A mugwump is, according to Wiktionary, a politician who sits on the fence, and has its roots in a native American word for leader from the Algonquian language. It came to mean a leader who was above the fray of party politics. In an article in the Sun, Foreign Secretary Boris Johnson wrote:
"The biggest risk with Jeremy Corbyn is that people just don't get what a threat he really is... They watch his meandering and nonsensical questions and they feel a terrible twinge of human compassion. Well, they say to themselves: he may be a mutton-headed old mugwump, but he is probably harmless.”
It may be that Johnson is using the phrase as an insult since Corbyn is rarely described as being above party politics. He later described Corbyn as representing "Islingtonian herbivorousness".