Longman Dictionary of Contemporary English
The Collaborative International Dictionary
Know-it-all \Know"-it-all`\, n. One who knows everything; hence, a person who makes pretension to great knowledge, especially one whose didactic conversational habit conspicuously reveals his belief that he has superior knowledge on many subjects; a wiseacre; a know-all; -- usually ironical. [Colloq. & pejorative]
Note: the use of this term implies that the speaker disapproves of this behavior, and may think that it is unjustified
Wiktionary
alt. (context chiefly US pejorative English) Someone who obnoxiously claims to be knowledgeable on a subject. n. (context chiefly US pejorative English) Someone who obnoxiously claims to be knowledgeable on a subject.
WordNet
n. someone who thinks he knows everything and refuses to accept advice or information from others [syn: know-all]
Wikipedia
Know-It-All is the debut album by Canadian singer Alessia Cara. It was released on November 13, 2015 through Def Jam. It follows the release of her extended play (EP) Four Pink Walls, which was regarded as a preview of the album.
Usage examples of "know-it-all".
It is electrophysiology and electrotherapy that will save mankind, not your clever know-it-alls who spend their time playing the great politician or, even more funny, daubing pictures.
Soon the smug-seeming, know-it-all debriefer from Hypo was irritating the returning hero by assuring him that long experience had demonstrated that in fact three normal-sized Solarian adults could fit in, though of course they would have to get rid of their space armor first.
For the present Brauksel, who is a know-it-all, prefers to have done with conjectures: for regardless of whether it was love or debentures that brought Lottchen Tiede into his house, and regardless of whether he sat in the Fishermen's Church in Bohnsack on Sundays as a baptized Jew or a baptized Christian, Albrecht Amsel, the dynamic merchant of the Lower Vistula, who, it might be added, was also the broad-shouldered cofounder of the Bohnsack Athletic Club reg.
There were a lot of know-it-all buttheads in Alcoholics Anonymous, but they were right about that.
But after only a couple of weeks, she'd come up with every cockamamie reason you could imagine why she couldn't keep it up—the midwives were all stupid slatterns, know-it-alls, impossibly superstitious, religious fanatics, there was too much of a language barrier, they all were filthy and the stench of a roomful of them gagged her.
Roberta scarcely trusted herself to remain on the porch lest she send Alda Quimby bouncing backward down its steps on her know-it-all, highfalutin' ass.
Ivan's no great businessman, but at least he listens to his manager and goes to Conrad or William… used to go, poor lamb… for advice, and has proper audits… but that know-it-all Forsyth, he went his own way and wouldn't listen to anybody and he bought a huge warehouse on a mortgage and thousands of lawn mowers that were supposed to cut the grass while you sat and watched, but they were already going out-of-date when he signed a contract for them, and also they kept breaking down.
That saucebox has the impudence to call me intransigent, stubborn, know-it-all, conceited.
But after only a couple of weeks, she'd come up with every cockamamie reason you could imagine why she couldn't keep it upthe midwives were all stupid slatterns, know-it-alls, impossibly superstitious, religious fanatics, there was too much of a language barrier, they all were filthy and the stench of a roomful of them gagged her, and on and on ad infinitum, ad nauseam.
I'm going to give you the fight of your life, whip the pants off you, and wipe that know-it-all look off your face!