Lewis & Short

ăb-ăvus, i, m.

      1. 1. (= avi avus, cf. Paul. ex Fest. p. 13 Müll.) Great-greatgrandfather, Plaut. Mil. 2, 4, 20; Cic. Brut. 58, 213; id. Har. Resp. 11, 22; 11, 38 (B. and K.); Dig. 38, 10, 1, § G; 10, § 15; called by Vergil quartus pater, A. 10, 619.
      2. 2. In gen., forefather, ancestor, Plin. 18, 6, 8, § 37; Sen. Clem. 1,10.