planum

Translingual

planum

(astronomy, planetology, planetography, astrogeography, astrogeology) an elevated plain or plateau on a moon or planet

From Latin plānum (“level ground, plain”).

planum (plural plana)

From plānus (“flat, even, level”).

plānum n (genitive plānī); second declension

Old French: plain
- → Dutch: plein
- → Middle English:
  - English: plain
  - Scots: plain
Italian: piano
Ibero-Romance:
- Old Galician-Portuguese: chão
  - Galician: chan, chá, chao
  - Portuguese: chão (see there for further descendants)
- Spanish: llano (see there for further descendants)
Borrowings:
- → Basque: lau
- → English: plain, plane
- → Galician: plano
- → Portuguese: plano
- → Spanish: plano

van der Sijs, Nicoline, editor (2010), “plein”, in Etymologiebank, Meertens Institute
“planum”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
planum in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
planum in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
Carl Meißner, Henry William Auden (1894) Latin Phrase-Book‎^[1], London: Macmillan and Co.
- to demonstrate, make a thing clear: aliquid planum facere (Ad Herenn. 2. 5)