vinculum

noun

1. 1

   A bond or link signifying union.

2. 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. 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. 4

   Specifically, the horizontal line between the numerator and denominator in a fraction.

5. 5

   A ligament that limits the movement of an organ or part.