Green’s Dictionary of Slang

an imaginary town, characterized by extreme dullness or boredom; thus a state, environment or situation of extreme dullness.

1960		N.Y. Times Mag. 28 Feb. 94/4: -ville, suffix connoting a superlative notion and tacked on to words at will to intensify them as in ‘He’s from Dullsville’.
1969		Guardian Weekly 23 Jan. 4: Style-wise [...] it looks like backward to Dullsville for the next four years in the nation’s capital.
1980		Times 5 Dec. 1390/1: All his life he’s been a citizen of the East Midlands. [...] By the metropolis’s jeering estimates, of course, these are a [...] series of worthy, yes, but oh how meanly parochial dullsvilles.
1991		K. Kelley His Way 278: ‘Dullsville, Ohio’ was anywhere but Vegas and ‘a little hey-hey’ was a good time.
2004		D.A. Debity Please Mama Please 114: No thanks; they were dooming us to dullsville! I had enough dullsville without adding to it.

(orig. US) tedious.

1957		M. Shulman Rally Round the Flag, Boys! (1959) 53: Dullsville [...] Everything dullsville. Geometry. Town meetings. Her dad. Her toes. Everything.
1966		Time 7 Oct. 17: Johnson is square, folksy and dullsville, sounding like dozens of boring politicians from the past.
1978		Oxford Times 13 Jan. 11/6: January and February are traditionally ‘dullsville’ months in restaurants and pubs and clubs.
1986		J. Kesler Parents and Children 506: As a child might phrase it, life in most families is ‘dullsville.’.
1998		A. Pistorius Everything You Need to Know About Birding 215: High summer, most birders agreed, was Dullsville, and they cased their binoculars.
2002		R.G. Barrett Mystery Bay Blues 78: It might be dullsville at times, Les. But when you walk out to your car in the morning, it’s still there.
2005		M. Salvatore Pitifer Return to Forever 191: Compared to Jesus, Buddha is kind of dullsville.

(US) a dullard.

1829		T. Curtis London Encyc. 540: A dullard, or dullhead, is a block-head.
1904		F.R. Stockton Novels and Stories 307: Don’t you know, you dullhead, that our good King George has issued a proclamation.
1930		R. Warren Prairie President 67: his driver, seeing the donkey thus stop, laid his whip lustily about its hindquarters, and cried: ‘O you perverse dullhead!’.
1973		G. Sheehy Hustling 179: I’m very nice, dullhead.
1989		H. Rawson Dict. of Invective (1991) 129: A slow-witted person may also be called a dullhead or described as a citizen of Dullsville.

a fool, a dullard.

c.1698

B.E. Dict. Canting Crew.

see under swift n.