Webster’s Revised Unabridged Dictionary · 1913
Aver
A′ver (ā′vẽr), n. [OF. aver domestic animal, whence LL. averia, pl. cattle. See Habit, and cf. Average.] A work horse, or working ox. [Obs. or Dial. Eng.]
A·ver′ (ȧ·vẽr′), v. t. [imp. & p. p. Averred (ȧ·vẽrd′); p. pr. & vb. n. Averring.] [F. avérer, LL. adverare, averare; L. ad + versus true. See Verity.] 1. To assert, or prove, the truth of. [Obs.]
2. (Law) To avouch or verify; to offer to verify; to prove or justify. See Averment.
3. To affirm with confidence; to declare in a positive manner, as in confidence of asserting the truth.
It is sufficient that the very fact hath its foundation in truth, as I do seriously aver is the case. Fielding.
Then all averred I had killed the bird. Coleridge.
Syn. — To assert; affirm; asseverate. See Affirm.