a. [ L. arduus steep, high; akin to Ir. ard high, height. ] 1. Steep and lofty, in a literal sense; hard to climb. [ 1913 Webster ]

Those arduous paths they trod. Pope. [ 1913 Webster ]

2. Attended with great labor, like the ascending of acclivities; difficult; laborious; as, an arduous employment, task, or enterprise. [ 1913 Webster ]

Syn. -- Difficult; trying; laborious; painful; exhausting. -- Arduous, Hard, Difficult. Hard is simpler, blunter, and more general in sense than difficult; as, a hard duty to perform, hard work, a hard task, one which requires much bodily effort and perseverance to do. Difficult commonly implies more skill and sagacity than hard, as when there is disproportion between the means and the end. A work may be hard but not difficult. We call a thing arduous when it requires strenuous and persevering exertion, like that of one who is climbing a precipice; as, an arduous task, an arduous duty. “It is often difficult to control our feelings; it is still harder to subdue our will; but it is an arduous undertaking to control the unruly and contending will of others.” [ 1913 Webster ]

adv. In an arduous manner; with difficulty or laboriousness. [ 1913 Webster ]

n. The quality of being arduous; difficulty of execution. [ 1913 Webster ]

a. [ L. assiduus, fr. assid&unr_;re to sit near or close; ad + sedēre to sit. See Sit. ] 1. Constant in application or attention; devoted; attentive; unremitting. [ 1913 Webster ]

She grows more assiduous in her attendance. Addison. [ 1913 Webster ]

2. Performed with constant diligence or attention; unremitting; persistent; as, assiduous labor. [ 1913 Webster ]

To weary him with my assiduous cries. Milton. [ 1913 Webster ]

Syn. -- Diligent; attentive; sedulous; unwearied; unintermitted; persevering; laborious; indefatigable. [ 1913 Webster ]

As*sid"u*ous*ly, adv. -- As*sid"u*ous*ness, n. [ 1913 Webster ]

a. [ L. caeduus, fr. caedere to cut down. ] Fit to be felled. [ Obs. ] Eyelyn. [ 1913 Webster ]

a. [ L. deciduus, fr. dec&unr_;dere to fall off; de- + cadere to fall. See Chance. ] (Biol.) Falling off, or subject to fall or be shed, at a certain season, or a certain stage or interval of growth, as leaves (except of evergreens) in autumn, or as parts of animals, such as hair, teeth, antlers, etc.; also, shedding leaves or parts at certain seasons, stages, or intervals; as, deciduous trees; the deciduous membrane. [ 1913 Webster ]

n. The quality or state of being deciduous. [ 1913 Webster ]

a. [ L. dividuus divisible, divided, fr. dividere. ] Divided; dividual. [ R. ] [ 1913 Webster ]

He so often substantiates distinctions into dividuous, selfsubsistent. Coleridge. [ 1913 Webster ]

n. [ It. duo, fr. L. duo two. See Duet. ] (Mus.) A composition for two performers; a duet.

a., n. See Dodecahedral, and Dodecahedron. [ 1913 Webster ]

a. [ L. duodecennis; duodecim twelve + annus year. ] Consisting of twelve years. [ R. ] Ash. [ 1913 Webster ]

a. [ L. duodecim twelve. See Dozen. ] Proceeding in computation by twelves; expressed in the scale of twelves. -- Du`o*dec"i*mal*ly, adv. [1913 Webster]

n. 1. A twelfth part; as, the duodecimals of an inch. [ 1913 Webster ]

2. pl. (Arch.) A system of numbers, whose denominations rise in a scale of twelves, as of feet and inches. The system is used chiefly by artificers in computing the superficial and solid contents of their work. [ 1913 Webster ]

a. [ L. duodecim twelve + findere to cleave. ] Divided into twelve parts. [ 1913 Webster ]

a. [ L. in duodecimo in twelfth, fr. duodecimus twelfth, fr. duodecim twelve. See Dozen. ] Having twelve leaves to a sheet; as, a duodecimo from, book, leaf, size, etc. [ 1913 Webster ]

n.; pl. Duodecimos A book consisting of sheets each of which is folded into twelve leaves; hence, indicating, more or less definitely, a size of a book; -- usually written 12mo or 12°. [ 1913 Webster ]

a. [ L. duo two + &unr_; decuple. ] Consisting of twelves. Arbuthnot. [ 1913 Webster ]

a. [ Cf. F. duodénal. ] Of or pertaining to the duodenum; as, duodenal digestion. [ 1913 Webster ]

a. [ L. duodenarius, fr. duodeni twelve each: cf. F. duodénaire. ] Containing twelve; twelvefold; increasing by twelves; duodecimal. [ 1913 Webster ]

‖n. [ NL., fr. duodeni twelve each: cf. F. duodenum. So called because its length is about twelve fingers' breadth. ] (Anat.) The part of the small intestines between the stomach and the jejunum. See Illust. of Digestive apparatus, under Digestive. [ 1913 Webster ]

n. [ L. duo two + -graph. ] (Photo-engraving) A picture printed from two half-tone plates made with the screen set at different angles, and usually printed in two shades of the same color or in black and one tint. [ Webster 1913 Suppl. ]

a. [ L. duo two + E. literal. ] Consisting of two letters only; biliteral. Stuart. [ 1913 Webster ]

‖n. [ It. See Done. ] A cathedral. See Dome, 2. [ 1913 Webster ]

Of tower or duomo, sunny sweet. Tennyson. [ 1913 Webster ]

n. [ L. duo two + tone. ] (Photoengraving) Any picture printed in two shades of the same color, as duotypes and duographs are usually printed. [ Webster 1913 Suppl. ]

n. [ L. duo two + type. ] (Photoengraving) A print made from two half-tone plates made from the same negative, but etched differently. [ Webster 1913 Suppl. ]

a. [ Gastro- + -duodenal. ] (Anat.) Pertaining to the stomach and duodenum; as, the gastroduodenal artery. [ 1913 Webster ]

n. [ NL. See Gastroduodenal, and -itis. ] (Med.) Inflammation of the stomach and duodenum. It is one of the most frequent causes of jaundice. [ 1913 Webster ]

a. Not deciduous or falling, as the leaves of trees in autumn; lasting; evergreen; persistent; permanent; perennial. Opposite of deciduous. [ 1913 Webster ]

The indeciduous and unshaven locks of Apollo. Sir T. Browne. [ 1913 Webster ]

a. [ L. occiduus, fr. occidere to go down. ] Western; occidental. [ R. ] Blount. [ 1913 Webster ]

a. [ L. prociduus. ] Falling from its proper place. [ 1913 Webster ]

a. [ L. residuus. ] Remaining; residual. Landor. [ 1913 Webster ]

a. [ L. succiduus, fr. succidere to fall under. ] Ready to fall; falling. [ R. ] [ 1913 Webster ]