Definition of oppugn in English:

oppugn

verb

[WITH OBJECT]formal
  • Question the truth or validity of.

    ‘the officials whose judgement was oppugned’
    • ‘He declared that the citizens of Boston ‘were disaffected to the Laws of the Land’ and were in a state of ‘open Rebellion, Disobedience, and Disloyalty,’ and that the clergy were foremost in ‘oppugning the Authority of the Laws of the Land.’’

Origin

Late Middle English (in the sense ‘fight against’): from Latin oppugnare ‘attack, besiege’, from ob- ‘against’ + pugnare ‘to fight’.

Pronunciation

oppugn

/əˈpjuːn/