The name of the line between the numerator and denominator in a fraction is:

• Fraction Bar
• Vinculum
• Virgule
• Separatrix
• Slash
• Forward Slash
• Solidus
• Diagonal
• Thingamajig
• Numerator Underline
• Denominator Overline
• Dividing Line
• The Middle Way

Note: The Wikipedia definition of Vinculum referring to this line is challenged in the Talk section.