arduus

Arduus (from ὀρθός) means difficult to ascend, in opp. to pronus; on the other hand, difficilis means difficult to execute, in opp. to facilis. Arduus involves a stronger notion of difficulty, and denotes the difficult when it borders on the impossible. Plin. Ep. iv. 17. Est enim res difficilis ardua. Tac. Hist. ii. 76. Æstimare debent, an quod inchoatur, reipublicæ utile, ipsis gloriosum, aut promptum effectu, aut certe non arduum sit. Cic. Verr. i. 51. Cum sibi omnes ad illum allegationes difficiles, omnes aditos arduos, ac pæne interclusos, viderent. (ii. 105.)

1. Altus denotes, as a general expression, height or depth, as mathematical dimensions, in opp. to length and breadth, and, consequently, height, in opp. to humilis; Cic. Tusc. v. 13. 24. Orat 57. N. D. ii. 47, like ὑψηλός; editus denotes height, in opp. to planus, Tac. Ann. xv. 38: lastly, procerus denotes height or length in reference to growth. The altum has no measure and no limits; the editum has the bulk of a hill; the procerum has the bulk of a tree, the full stature of the human figure, and so forth. 2. Altus, editus, and procerus, denote height merely in relation to space; arduus means height, which is at the same time steep and inaccessible; thence, figuratively, ‘difficult, impossible;’ celsus, height, that thrusts itself out, and stretches upwards; thence, figuratively, ‘proud;’ excelsus and præcelsus, what overtops something that is itself high, hence ‘pre-eminent;’ sublimis, what is on high without touching the ground, soaring in the air, like μετέωρος; thence, figuratively, ‘grand,’ of an elevated nature. (ii. 99.)