separatrix

[ sep-uh-rey-triks, sep-uh-rey- ]
/ ˈsɛp əˌreɪ trɪks, ˌsɛp əˈreɪ- /

noun, plural sep·a·ra·tri·ces [sep-uh-rey-tri-seez, -er-uh-trahy-seez] /ˌsɛp əˈreɪ trɪˌsiz, -ər əˈtraɪ siz/, sep·a·ra·trix·es.

something that divides or separates, as the line between light and dark areas on a partially illuminated surface.
Mathematics. one of several symbols for separating components of a number, as a decimal point or comma.

Origin of separatrix

1650–60; < New Latin sēparātrīx, Late Latin; see separator, -trix
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for separatrices

separatrix

/ (ˈsɛpəˌreɪtrɪks) /

noun plural separatrices (ˌsɛpəˈreɪtrɪˌsiːz)

another name for solidus (def. 1)

Word Origin for separatrix

via New Latin from Late Latin, feminine of sēparātor one that separates
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012