Negro 是比較中性的一個詞， 但是你裏麵用的 N word 是最有侮辱性的一個詞，盡管偶然可能一些黑人自己會調侃的用這個詞， 但是其他人應該絕對不用。
http://en.wiktionary.org/wiki/nigger
Usage notes
Today the word "nigger" is potentially extremely offensive and, particularly in the United States, politically inflammatory. Although it has to some extent been reclaimed by some persons of African descent, its use is contentious and fraught, particularly when used by non-blacks.
"Nigger" has taken on pejorative qualities, as it implies not only darkness of skin, but a general lack of intelligence and sophistication. At the time of the word's origin, various English-speaking North American settlers who set cultural standards considered black people fundamentally inferior and less civilized than white people. The term is generally considered offensive to black people, not only because it singles them out on the basis of their skin colour, but also because, due to its origin, it carries connotations of slavery, inferiority and oppression.
The term is generally derogatory when used by persons not of African descent (and sometimes when used by persons of African descent), but, it is also used by some black people among themselves, positively, especially when used in the form of "nigga," in a form of reclamation. It is important to note that many people do not believe that "nigger" is able to be reclaimed, because of its fraught history and continued pejorative usage. Usage by non-blacks, however, is almost invariably considered offensive. Thus, the term is both potentially liberatory while also being highly contested.
In its pejorative sense, it arguably ranks as the most insulting racial epithet in the English language, with strong connotations of cultural and intellectual inferiority or deficiency. The controversial nature of the word makes it unacceptable for use in most modern mainstream American media. The word is usually censored in direct quotations or euphemistically referred to as the "n-word" to blunt its potential negative impact.
