The definitions of the words 'black' and 'white' are extremely polarized not only in meaning, but also in context of phrases. An example of the sharp difference between the two colors in a phrase is 'white magic' and 'black magic'. As a general trend, the dictionary uses the word 'white' to define all that is good and pure and 'black' to refer to evil or dirty wrongdoings. Another example is the use of the color white in weddings and black for mourning a death. It should be noted that this trend of using black for bad and white for good is not however a global tendency.
Many Mexican cultures wear black to weddings and white to funerals.
Nevertheless, this tendency can be found in America and it does shed some light on the way people need to sharply polarize issues dealing with Black and White races. Instead she relied on the reader's definitions of black and white as the means of determining the race of the characters. Both the dictionaries referred to gave a negative definition to 'black'. These negative dictionary definitions reflect the mentality of the society from which the dictionary comes from. Anybody who decided that Twyla was black may have been unconsciously applying the definition of 'black' as it is defined in English dictionaries.