Vinculum /(?)/

pl. Vincula, Vinculums

1. A bond of union; a tie.
2. A straight, horizontal mark placed over two or more members of a compound quantity, which are to be subjected to the same operation, as in the expression x² + y² - x + y. (Math.)
3. A band or bundle of fibers; a fraenum. (Anat.)
4. A commissure uniting the two main tendons in the foot of certain birds. (Zool.)