Definition of "whopper"

I’d gone out pike fishing, bless you, never thinking of a trout, and when I saw that whopper on the end of my line, blest if it didn’t quite take me aback. Well, you see, he weighed twenty-six pound.

1889, Jerome K. Jerome, chapter 17, in Three Men in a Boat […] ‎

I’ve just run down from Ulster County to look at the town, bein’ that the hayin’s over with. Gosh! but it’s a whopper. I thought Poughkeepsie was some punkins; but this here town is five times as big.

1910, O. Henry [pseudonym; William Sydney Porter], “The Poet and the Peasant”, in Strictly Business‎

There's a storm blowing up, Sylvester—a 'whopper', speaking in the vernacular of the peasantry.

1939, Noel Langley, Florence Ryerson, Edgar Allan Woolf, The Wizard of Oz

When he got done telling it there was one of them uncomfortable silences that comes, you know, when a person has been telling a whopper and you feel sorry for him and wish you could think of some way to change the subject and let him down easy, […]

1894, Mark Twain, chapter XII, in Tom Sawyer Abroad

Coming out with a whopper now. Rhapsodies about damn all. Believes his own lies. Does really. Wonderful liar. But want a good memory.

1922 February, James Joyce, Ulysses, Paris: Shakespeare and Company, […]

Isuzu Inc. hit pay dirt in the late '80s with its series of “Joe Isuzu” spots, featuring an oily, Satanic-looking salesman who told whoppers about Isuzu's genuine llama-skin upholstery and ability to run on tapwater.

1997 , David Foster Wallace, “E Unibus Pluram: Television and U.S. Fiction”, in A Supposedly Fun Thing I’ll Never Do Again: Essays and Arguments, Boston, Mass.: Little, Brown and Company