The term profanity refers to word choices or usages which many consider to be offensive. The original meaning of the term was restricted to blasphemy, sacrilege or taking God's name in vain, especially expressions such as "God damn it". However, the meaning has been extended to include scatalogical or sexual terms (in English, primarily "fuck", "shit", "piss", "cunt", "faggot").
At the same time some words originally considered profane, have become much less offensive with the increasing secularity of society, while others have become increasingly taboo. "Nigger", for example, was accepted in some subcultures where it is far less so today.
Terms of profanity have historically been taboo words, though they are losing their taboo status. (The primary exception is the word "cunt", which maintains much of its taboo status at least partly due to the influence of feminism, though other feminists are attempting to "reclaim" a neutral or complimentary status for this word). However, in modern times new words have become taboo to replace these, primarily racial or ethnic epthitets.
This especially applies to the English word "nigger", which to many people today is much more offensive to the ears than sexual or scatalogical terms. (Although it depends on the context in which it is used -- people of African descent sometimes use the term among themselves as an badge of pride.) This sensitivity to the word "nigger" has even extended to the point of attempting to ban the use of the word "niggardly", which many mistakenly believe to be related to the word "nigger".
Psycholinguistic studies have demonstrated that profanity and other taboo words produce physical effects in people who read or hear them, such as an elevated heart rate.
This fact is seen by some as evidence that reclaiming of words such as "queer" is a valid way to remove its power.