A simple search of DDG found multiple Jewish sources using and explaining the use of the word 'zionist' as an adjective for individual persons e.g.
The Times of Israel: "To be a Zionist means to recognise the land of Israel as the ancestral homeland of the Jewish people and to believe in the existence of a Jewish state in the land of Zion, or Israel."
I didn't say "Websters Dictionary defines" - I showed that the word is in common usage as a non-perjorative by Jewish sources