A true dictionary shouldn't have a single definition for two words like that. Black/White are adjectives which are used to describe a noun, [nationalist]. To learn the true definition you would need to simply look up the noun itself. Merriam-webster fancies itself as a hybrid dictionary/encyclopedia it would seem. https://www.merriam-webster.com/dictionary/nationalist Dictionary.com is no different https://www.dictionary.com/browse/nationalist Cambridge on the other hand appears legitimate. https://dictionary.cambridge.org/ Search white or black nationalist and it returns a page with words similar to 'nationalist', but it does not make an attempt to define two words.