The eighteen Armanen runes are the work of Guido von List, published in 1908. Describing one honestly means naming the historical character underneath and the changes he made.
The character behind it
Nauth corresponds to the Younger Futhark character whose Old Norse name was naud, meaning need, distress or constraint. All three of the medieval rune poems treat their equivalent character in this register: hardship, a hard choice, something endured. It is one of the few runes whose gloss is consistent across the Norse and English traditions.
What von List did with it
He kept the N value, Germanised the name, and fitted the character into his own scheme of eighteen. Where the historical glosses were already consistent he had less room to reinterpret, which makes this one of the runes where his row and the medieval material sit closest to one another.
The frame around the whole row
Von List described the eighteen as an ancient Germanic priestly alphabet that he had recovered, and set the count to match the eighteen rune-charms of the Havamal. No historical futhark has eighteen characters. Runologists treat the row as an esoteric construction of the early twentieth century.
Reception
The row was afterwards taken up in volkisch circles and by National Socialist organisations in the 1930s and 1940s, a documented history that this atlas records rather than passing over.