(N) SHVITZ-urd  A day of extreme summer heat, humidity and sun that is so flattening and debilitating that it might as well be a blizzard. USAGE: In the first weeks of September, New York was hit by a powerful shvitzard, with day after day of blinding sun, temperatures in the 90s, and humidity so high that air conditioners could barely function. Those who attempted to go out in the shvitzard quickly learned their folly.