Euphemism (yū’fə-mĭz’əm) is a polite or agreeable word that is used to replace a possibly offensive or harsh one. It can also refer to a word or expression that under estimates the real state of things.
But after the September 11th attacks, its Self-Defence Forces (SDF is a euphemism for its armed forces that gets round its pacifist-sounding constitution) have been deployed in much more determined fashion. (The Economist)
The British have some rather wonderful euphemisms. Try “one sandwich short of a picnic” for “crazy” or “NQOCD” instead of “not quite our class dear.” And how about “sugar on your strawberries,” meaning that senility may be just around the corner? (NY Times)