arduus

From a Proto-Italic *arðwos, from Proto-Indo-European *h₃r̥dʰwós, from *h₃erdʰ- + *-wós (whence Latin -uus). 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.d̪u.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.