ob-sum, obfui or offui, obesse (old form of fut. obescet, oberit vel aderit, Paul. ex Fest. p. 188 Müll.), v. n., to be against, be prejudicial to; to hinder, hurt, injure; opp. to prodesse (cf.: officio, noceo, injuriam facio; class.): Ty. Nunc falsa prosunt. Heg. At tibi oberunt, Plaut. Capt. 3, 5, 48; Ter. Hec. 3, 5, 13; cf.: men obesse, illos prodesse, Enn. ap. Cic. Div. 1, 31, 66 (Trag. v. 84 Vahl.); and: qui (pudor) non modo non obesset ejus orationi, sed etiam probitatis commendatione prodesset, Cic. de Or. 1, 26, 122: subicimus id. quod nobis adjumento futurum sit, aut offuturum illis e contrario. Auct. Her. 4, 23, 33: obsunt auctoribus artes, Ov. M. 7, 562: ne prodigus obsit, Verg. G. 4, 89.
With a subject-clause: nec, dum degrandinat, obsit Agresti fano supposuisse pecus, Ov. F. 4, 755: nihil obest dicere, Cic. Fam. 9, 13, 4.