separatrix

== English == === Etymology === Learned borrowing from Latin sēparātrīx, the feminine form of separator (originally owing to an implied līnea (“line”)), from sēparāre (“to divide; to separate”) + -trix (forming female agents). By surface analysis, separate +‎ -trix. First developed as a decimal mark among the medieval Arab mathematicians, whence a shorter variant gave rise to the decimal comma employed by many European countries and their former colonies. === Pronunciation === IPA(key): /sɛpəˈɹeɪtɹɪks/ Rhymes: -eɪtɹɪks === Noun === separatrix (plural separatrixes or separatrices) (typography, historical) The ⟨L⟩ or pipe ⟨|⟩ mark formerly used to divide integers from decimals. Synonyms: pipe, slash Hypernyms: decimal mark < radix point < point, mark, character, separator Coordinate terms: decimal point (precise sense), decimal comma (typography, obsolete) Synonym of decimal point, which replaced such marks. (typography) The proofreader's mark resembling a slash ⟨ / ⟩ or vertical bar ⟨ | ⟩ placed after a note in the margin to indicate that it should replace the item(s) struckthrough in the running text or to separate it from other margin notes. A terminator: a line on a partially-illuminated surface separating the lit and shaded regions. (physics) The line between regions having different magnetic fields. (mathematics) The boundary separating two modes of behavior in a differential equation. === Further reading === separatrix on Wikipedia.Wikipedia separatrix (mathematics) on Wikipedia.Wikipedia Merriam-Webster Online. "separatrix". Accessed 11 February 2016. Oxford English Dictionary, 1st ed. "separatrix, n." Oxford University Press (Oxford), 1912. “separatrix, n.”, in OED Online ⁠, Oxford: Oxford University Press, launched 2000.