Steinerian

In algebraic geometry, a Steinerian of a hypersurface, introduced by Steiner (1854), is the locus of the singular points of its polar quadrics.

References

• Coolidge, Julian Lowell (1959) [1931], A treatise on algebraic plane curves, New York: Dover Publications, ISBN 978-0-486-49576-7, https://books.google.com/books?id=Y7WEf6V0XwgC 
• Dolgachev, Igor V. (2012), Classical Algebraic Geometry: a modern view, Cambridge University Press, ISBN 978-1-107-01765-8, http://www.math.lsa.umich.edu/~idolga/CAG.pdf 
• Steiner, Jakob (1854), "Allgemeine Eigenschaften der algebraischen Curven." (in German), Journal für die Reine und Angewandte Mathematik 47: 1–6, doi:10.1515/crll.1854.47.1, ISSN 0075-4102, https://zenodo.org/record/1448868/files/article.pdf