(noun) A less offensive word substituted for an offensive one. (Essa frase é "tricky": Uma palavra menos ofensiva que entra no lugar de uma ofensiva)

Words referring to the semantic extremes of the holy and the profane are often taboo. To circumvent (já topei uma meia dúzia de vezes com esse "circumvent" em contratos) the impediment this raises, we replace the prohibited words with more acceptable ones, called "euphemisms."

Ex.: "God," as an interjection, for example, is replaced by "golly," and "heck" replaces "hell." One is too holy to be uttered, the other, too profane. In Britain, "bloody" is considered vulgar, so "ruddy" has replaced it: "He's a right ruddy blighter, he is." A person given to using euphemisms (euphemizing) is a "euphemist" or "euphemizer." Euphemisms are "euphemistic" terms and we use them "euphemistically."

Today, euphemisms are widely used to replace any unpleasant or potentially offensive word. Not only are there a plethora of euphemisms for "drunk" (high, pickled, tipsy, snockered) and kill (eliminate, rub out, off, remove), but also for words that refer to jobs and conditions with negative connotations, e.g. "janitor" (custodian), "crippled" (impaired), "to fire" (to lay off), "insane" (mentally ill). In fact, "pork," "beef," and "mutton" are all euphemisms for "pig meat," "cow meat," and "sheep meat" borrowed from French porc "pig", boeuf "ox", and mouton "sheep."
Source: Dr. Language