A euphemism is the substituion of an inoffensive expression, or one with favourable associations, for an expression that may offend because of its disagreeable associations.

Pass away is a euphemism for die , put (animals) to sleep for kill , perspire for sweat, nurse for suckle, agent for spy, dentures for false teeth .

Euphemisms are particularly common for the process of reproduction and excretion and for activities, people, and bodily parts involved in those processes. People vary in what they consider to be offensive, and toleration for blunt language also varies from period to period. A euphemism may eventually acquire unpleasant associations and give way to later euphemisms: toilet and lavatory , themselves euphemisms, are frequently replaced by othe euphemisms, such as cloakroom.

Euphemisms can be used legitimately for politeness and tact, but they are dishonest when they are used to avoid facing unpleasant activities or to conceal and deceive. Dishonest uses are frequent in political and military language: Hitler's plan for the extermination of the Jews was called the final solution, protective custody has been used for imprisonment, industrial action for strikes, police action for war and armed reconnaissance for bombing .

This is a kind of euphemism, which means the substitution of a mild and indirect expression for one that may be offensive. Many euphemisms are entirely justified. We use them not only for decency, with reference to bodily parts and functions, but out of generous feeling towards people whom we should otherwise have to call poor, fat, old, crippled, stupid (See also "Политическая корректность, или Языковой такт" ). But the kind of euphemism here called genteelism is favoured by people who think the frank and obvious word is vulgar. Since the most effective users of the language are seldom afraid of being frank (or even abrupt when the occasion warrants it), it is a mistake to try to sound genteel.

По материалам "Longman Guide to English Usage" 2004