Vinculum

1. n. A commissure uniting the two main tendons in the foot of certain birds.
2. n. A bond of union; a tie.
3. n. 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.
4. n. A band or bundle of fibers; a fraenum.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.