Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
"old-fashioned person," 1871, American English, of uncertain origin.
Wiktionary
n. (context US informal English) An old-fashioned, persnickety or ineffective person.
WordNet
n. a bore [syn: stuffed shirt]
Wikipedia
A fuddy-duddy (or fuddy duddy or fuddy-dud) is 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.
Usage examples of "fuddy-duddy".
He laughed at himself for being like a conventional old fuddy-duddy, and then he saw Belgrade Road ahead of him, debauching at a right angle from the main street.
If some old fuddy-duddy is now chairman and can't conduct a meeting properly you can always carry out basic business in a committee-of-the-whole, with your own choice as chairman of the committee-of-the-whole - or you can through an executive committee - or provide the office of parliamentarian-or even teach him some parliamentary law if you are subtle about it.
Carol was saying in a low voice—just in case any of the fuddy-duddies, who thought tossing a horseshoe at an iron peg was an exciting way to spend the day, had sharp ears.
There were some old curmudgeons on the faculty-and some young fuddy-duddies, too-who objected to Owen's style.
This place needs new stands and a whole new outlook, and what it doesn't need is a fuddy-duddy old colonel for a manager and a stick-in-the-mud Clerk of the Course who can't say boo to a doctor.