averring

/AH0 V ER1 IH0 NG/
verb
  1. 1

    To assert the truth of, to affirm with confidence; to declare in a positive manner.

  2. 2

    To prove or justify a plea.

  3. 3

    To avouch, prove, or verify; to offer to verify.

Source: https://en.wiktionary.org/wiki/aver, https://en.wiktionary.org/wiki/averring