1. To affirm; to declare with assurance, or plainly and strongly; to state positively; to aver; to asseverate. Nothing is more shameful . . . than to assert anything to be done without a cause. Ray. 2. To maintain; to defend. [Obs. or Archaic] That . . . I may assert Eternal Providence, And justify the ways of God to men. Milton. I will assert it from the scandal. Jer. Taylor...