Vinculum

noun

1. A bond or link signifying union.
2. Any symbol used to group some of the terms in an expression, indicating that that part of the calculation should be done before other parts.
3. A horizontal line over the top of some of the terms in an expression, indicating that that part of the calculation is to be done before other parts.
4. Specifically, the horizontal line between the numerator and denominator in a fraction.
5. A ligament that limits the movement of an organ or part.