wonk

Etymology

American English student slang 1954; perhaps navy slang before that. "Expert" sense popularized in the Clinton administration, 1993. Origin uncertain, possibly from wonky (“shaky, unreliable”) or wank, wanker or simply expressive.

noun

1. (derogatory, informal) An overly studious person, particularly a student.
   Previously, e-reading had been the domain of early adopters and new technology wonks. 2014, Catherine Sheldrick Ross, Pleasures of Reading, The: A Booklover's Alphabet, page 53
2. (by extension, informal) A policy wonk or other intellectual expert.
   This is the sort of standard that the Paul Ryans of the world trumpet to their constituents, to potential campaign contributors and to their peers in Congress. They become “budget wonks” and political superstars, even if their proposals are bound to go nowhere. 2014-03-14, Dean Baker, “Paul Ryan isn't the wonk of Washington – it's time to listen to more good ideas”, in The Guardian