fiveleaves - // "People of colour" and a "coloured person" mean exactly the same thing. English puts an adjective before the noun, wheras French puts it afterwards. A green apple, un pomme vert means the same thing //
The vital aspect about using language is context and interpretation.
You can refer to a black person as 'coloured' and be grammatically correct, because a black person is coloured, and that colour is a shade of black.
But being grammatically correct while simultaneously ignoring the cultural impact of the term you are using means that you are putting the importance of language over and above the interpretation and meaning of the language you are using.
If you live on an island, or a high-level academic institution where such things are more important, then you can do that with no problem.
But in the real world, where the majority of people live, and speak, and understand each other, living in a society gives you the responsibility of sensitivity to its attitudes, and not giving gratuitous offence simply in order to be right.
You could use the term 'nigra' and argue that is it the result of the corruption of the word '***' by the accent enjoyed by Americans from the southern states - and you would be quite right, gramatically.
But try using it on a street corner in Harlem, and see how important being 'right' is when you balance it against the very real possibility of being hospitalised by any of members of the public around who heard you!