Definition of "BVDs"

The dealers apparently got a big inventory and since the war all nobody seems to be buying pajamas. Learned to sleep in their ‘BVDs’ during the war years in the armed services all these young men did.

1953, Richard Bissell, “7½ Cents”, in Atlantic, Little, Brown, page 53

Thus, the light switched on, there was Einhorn in his BVDs, wasted arms freckled, grizzled hair afly from his face that was inclined to flatness, the shrewd curved nose and clipped mustache.

1953, Saul Bellow, chapter 5, in The Adventures of Augie March, New York: Viking Press, pages 64–65

We frolicked like dolphins – Graeme and I in shorts and Bob in his B.V.D.'s – and then stretched out on the ancient waveworn shingle to let the sinking sun dry and warm us.

1970, John Glassco, Memoirs of Montparnasse, New York, published 2007, page 97