separatrix

IPA: sˈɛpɝʌtrɪks

(typography, historical) The ⟨L⟩ or pipe ⟨|⟩ mark formerly used to divide integers from decimals.
(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.

Examples of "separatrix" in Sentences

My point is that the nature of the separatrix and that of the basins of attraction are somewhat separate issues.
Strong electric fields exist inside the separatrix regions and the electric potential drop across the regions can be up to several kV.
The observed strong electric fields and currents inside the separatrix region can be important for a local energization of ions and electrons, particularly of ionospheric origin, as well as for magnetosphere-ionosphere coupling.