If the numerator is written above the denominator, the line is called the "bar". If the fraction is written in-line like 1/2, the line is called a "virgule".
There is no recorded name for the line between universes.
The line between the numerator and the denominator of a fraction is the the solidus line
siegfried line
The line is called a diagonal if it is drawn between two nonadjacent angles.
That is a vinculum.
Mc-Mahon line
straight line.
The Durand line.
The solidus
Radcliffe Line
durand line
divider