High Quality Content by WIKIPEDIA articles! A vinculum is a horizontal line placed over a mathematical expression, used to indicate that it is to be considered grouped together. Vinculum is Latin for "bond", "fetter", "chain", or "tie", which is roughly suggestive of some of the uses of the symbol.The vinculum can be typed using the combining overline (U+0305) after the character that one wishes to add it to. For example, typing 33.333 ' with combining overlines over the final three 3's produces: 33.3 3 3 '. It can also be added over any given character or run of characters by using the CSS rule text-decoration: overline, although this does not carry over when pasting onto a plain text editor. In LaTeX, use 3.overline{333}....