# How do you say ‘nappe’ in Esperanto?

Wikipedia has a disambiguation page for this term. The sense that I am interested in is the mathematical one, that is, either half of a double cone. This term (for any of the senses) does not appear in Benson, nor in Wells, nor in Vikivortaro. Wikipedia mentions, and defines, this term in its article on ‘cone’, but does not have a separate article on it, and therefore if there is an article on it in Vikipedio it is not reachable from the sidebar of the English-language article. I went directly to Vikipedio and tried bringing up the term with a few guesses, such as ‘napo’, ‘napeo’, and ‘napio’, but to no avail. I did the same with the online PIV, again to no avail. So, how should the mathematical sense of ‘nappe’ be rendered in Esperanto?

• I think a new word will have to be invented for that. Feb 1, 2017 at 16:56

Note that for mathematical terminology, ReVo is much more trustworthy than either PIV or Vikipedio, as it contains the full content of the Matematika vortaro kaj oklingva leksikono by Marc Bavant, the best source of mathematical terms in Esperanto. According to the definition in ReVo, konuso – when used to refer to a surface rather than a solid – actually means double cone (see definition a)), and the half of this surface that borders a solid cone is called duona konuso (see definition b)). Additionally, a comment after the definitions clarifies that one should use konusa surfaco or konusa solido in case there is a risk of misunderstanding about which meaning is meant. If I correctly understand the English nappe, it always refers to a surface, and never to a solid. So following this terminology, one should say either duona konuso or duonkonusa surfaco for a nappe.

• I'm going with 'duona konuso'. I've up-voted your answer, and accepted it. Much thanks for sharing your research. Feb 2, 2017 at 16:20

The word nappe ("tablecloth") is just the French term for a sheet of a surface.

In English we normally say, for example, hyperboloid of one sheet rather than one nappe.

Because a double cone is connected at the vertex, there seems to be hesitation about whether it is in one or two sheets, and this may have led people to follow French books of geometry and say it is in two nappes. However, I think it is probably not necessary in context to use a separate word.

In its entry for hiperbolo, PIV gives the examples unupeca, dupeca hiperboloido.

So my guess is that you could say la supra, suba peco de duoblakonuso.

Obviously, tuko and folio might be used, but peco is what they chose.

• I appreciate your input, and have upvoted your answer, but I think the terms 'supra' and 'suba' inappropriate, because they presume a certain orientation of the cone. Feb 2, 2017 at 16:23
• If you search nappe cone on Google Books, you will see that very often an orientation is assumed, and that upper and lower nappe are standard terms. Feb 2, 2017 at 20:04
• They may be standard terms, but they are not mathematical terms. I was going for a mathematical term. (Ordinary language and technical language are two separate things. We often mix the two for convenience, but the mixture is like that of oil and water.) Science is not a democracy. Feb 4, 2017 at 14:44

In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than 2 km (1.2 mi)... https://en.wikipedia.org/wiki/Nappe

I found this term tertavolo in ReVo, but I don't know.

tertavolo = Horizontala tavolo da tero

• This answer has nothing to do with what the question is about. Feb 2, 2017 at 9:24