How to resolve country and nationality entities?
I believe that Lemmatisation is the right thing. Anyways another way to do it is to use WordNet. For a word which its POS is Noun you can query if it has a member holonym, this feature will show the country which it belongs. For instance, Canadian -&gt; Canada. Then you have to be careful, cause if you take the member holonym of Canada that will be the British Commonwealth. I guess you could have a Levenshtein distance threshold to ignore these.

You can have a look on the online web app.