duplus

Inherited from Proto-Italic *duplos. By surface analysis, duo +‎ -plus.^[1] Cf. Ancient Greek διπλόος (diplóos, “double”), from δι- (di-), from δύο (dúo, “two”), + -πλόος (-plóos, “-fold”), and Proto-Germanic *twīflaz (“doubt”).

• (Classical Latin) IPA^(key): /ˈdu.plus/, [ˈd̪ʊpɫ̪ʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈdu.plus/, [ˈd̪uːplus]

duplus (feminine dupla, neuter duplum); first/second-declension adjective

1. double (twice as much, or as big)

First/second-declension adjective.

• duplō (Late or Legal Latin)

• Italo-Romance:
  • Italian: doppio
    • → Sardinian: dopiu
• Padanian:
  • Gallo-Italic:
    • Ligurian: doggio
    • Lombard: dopi
    • Piedmontese: dobi
  • Friulian: dopli
  • Romansch: dubel, dobel
  • Venetan: dopio, dupio
• Gallo-Romance:
  • Catalan: doble
  • Franco-Provençal: doblo
  • Old French: doble (see there for further descendants)
  • Occitan: doble
• Ibero-Romance:
  • Asturian: doble, duble, doblu, dublu
  • Old Galician-Portuguese: dobro
    • Galician: dobre
    • Portuguese: dobre, dobro
  • Spanish: doble, doblo
• Borrowings:
  • → English: duple, duplo-
  • → Italian: duplo
  • → Portuguese: duplo
  • → Romanian: dublu
  • → Spanish: duplo
  • → Sicilian: dupru, duplu, dùbulu

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