arduus

Disputed.

• Perhaps from Proto-Italic *arðwos, from Proto-Indo-European *h₃r̥dʰwós, from *h₃erdʰ- + *-wós (whence Latin -uus). The development of the Latin term is slightly unusual, as the sequence *-rdʰ- typically produces Latin -rb. According to De Vaan, it is possible that *-w- in the pre-form may have prevented the development into a labial, thereby explaining the Latin term.^[1]
• Alternatively, the linguist Nicholas Zair derives the term from *h₂r̥Hdʰ-ew-, the weak stem of a Proto-Indo-European u-stem adjective. According to this theory, the term would follow a development from *h₂r̥Hdʰ-ew- > *aradʰ-ew- > *arad-ew-, whence ultimately arduus.^[2]
• The linguist Robert Woodhouse proposes that a sequence *Hh₃r̥dʰwo- could produce arduus via sound development of *HHC- to Latin aC-.^[3]

Cognate with Latin arbor (“tree”), Welsh ardd (“high; hill”), Old Irish ard (“high; height”), Ancient Greek ὀρθός (orthós, “upright, straight”), Sanskrit ऊर्ध्व (ūrdhvá, “rising upwards, high”).

• (Classical Latin) IPA^(key): [ˈar.du.ʊs]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈar.du.us]

arduus (feminine ardua, neuter arduum); first/second-declension adjective

1. lofty, high, steep, tall, elevated
2. hard to reach, difficult, laborious, arduous

   Nihil mortalibus ardui est.

   Nothing is hard for mortals. (Horace)

First/second-declension adjective.

• arduitās
• perarduus

• “arduus”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• “arduus”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
• “arduus”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.