Lewis & Short

ā-verrunco, āre, v. n., a very ancient word, peculiar to the lang. of religion, to avert, remove: uti calamitates intemperiasque prohibessis, defendas averruncesque, Cato, R. R. 141, 2: di averruncent, Att. ap. Cic. Att. 9, 2, A.: quorum (prodigiorum) averruncandorum causā supplicationes senatus decrevit, Liv. 10, 23, 1; 8, 6, 11: haec procul a nobis averruncetur amentia, Arn. 1, p. 18.
So in the old Optat. form averruncassint = averruncent, Pac. ap. Varr. L. L. 7, § 102 Müll.; in Paul. ex Fest. s. v. verruncent, p. 373 Müll. (Trag. Rel. p. 90 Rib.; by Non. p. 74, 23, erroneously ascribed to Lucilius); and in the very ancient inf. fut.: possum ego istam capite cladem averruncassere, Pac. ap. Non. p. 74, 25 (Trag. Rel. p. 106 Rib.).