Fuddy-duddy

"Fuddy-duddy" (or "fuddy duddy" or "fuddy-dud") is a term for a person who is fussy while old-fashioned, traditionalist, conformist or conservative, sometimes almost to the point of eccentricity or geekiness. It is a slang term, mildly derogatory but sometimes affectionate too and can be used to describe someone with a zealous focus on order.