delegitimate

From de- +‎ legitimate.

• (UK) IPA^(key): /ˌdiːlɨˈdʒɪtɨmeɪt/

delegitimate (third-person singular simple present delegitimates, present participle delegitimating, simple past and past participle delegitimated)

1. (transitive) To cause (something) not to be legitimate; to make illegitimate, to illegitimize.
   • 2016, Peter H. Wilson, The Holy Roman Empire, Penguin, published 2017, page 7:

     Equally, the arguments delegitimate rival claims both from insiders […] and from outsiders seeking hegemony over the ‘national’ territory.

• delegitimize