Definition of "wen"

There was a Fellow with a Wen in his Neck, larger than five Woolpacks, and another with a couple of wooden Legs, each about twenty foot high.

1726 October 28, [Jonathan Swift], “The Country Described. […]”, in Travels into Several Remote Nations of the World. […] [Gulliver’s Travels], volume I, London: […] Benj[amin] Motte, […], part II (A Voyage to Brobdingnag), page 220

When I have met an immigrant tottering under a bundle which contained his all--looking like an enormous wen which had grown out of the nape of his neck--I have pitied him, not because that was his all, but because he had all that to carry.

1854, Henry David Thoreau, Walden, Walden

Creeps, foreigners with tinted, oily skin, wens, sties, cysts, wheezes, bad teeth, limps, staring or—worse—with Strange Faraway Smiles.

1973, Thomas Pynchon, Gravity's Rainbow

I am debating whether to risk scratching the right side of my jaw, where there is a wen.

1996, David Foster Wallace, Infinite Jest […], Boston, Mass., New York, N.Y.: Little, Brown and Company, page 4