Separatrix (from Latin, the feminine form of "separator") may refer to: Separatrix (decimal mark), an mark or vertical bar formerly used as a decimal point Separatrix, a proofreader's mark resembling the slash Separatrix in math, the boundary separating two modes of behaviour in a differential equation A mechanism for magnetically limiting a plasma, and hence for controlling the nuclear fusion in a tokamak; see divertor See also Separator (disambiguation)