Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* ărātro and contr. artro, āre, v. a. [aratrum], to plough after sowing: quod nunc vocant artrare, id est aratrare, Plin. 18, 20, 49, § 182.
ărātrum, i, n. [ἄροτρον], a plough (the inventor of which was Byzyges, acc. to Plin. 7, 56, 57, § 199; or Triptolemus, acc. to Verg. G. 1, 19. The parts of it were temo, stiva, manicula, vomer, buris, aures, and dentale. For a description of it, v. Verg. G. 1, 162 sqq.; Pauly’s Real-Ency. I. pp. 665 sq.; and Smith, Dict. Antiq.); Lucr. 1, 313; 5, 219: curvi moderator aratri, id. 5, 933, and id. 6, 1251; Cic. Rosc. Am. 18; id. Agr. 2, 25; id. N. D. 2, 63, 159; Verg. G. 1, 19; 1, 170 et saep.: imprimere aratrum muris, to press the plough into the walls (of a town), i. e. to turn a town into arable land, to destroy completely, Hor. C. 1, 16, 20; cf. Sen. Clem. 1, 26, 4; used for marking the boundaries of new towns, Cic. Phil. 2, 40: Aeneas urbem designat aratro, Verg. A. 5, 755, ubi v. Serv.; Cato ap. Isid. Orig. 15, 2; Inscr. Orell. 3683.