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{| class="wikitable" style="float:right" |- ! Description || Sample || Unicode || CSS/HTML |- | Overline(markup) | || | style="font-size:75%" | text-decoration: overline; |- | rowspan="2" | Overline(character) | ‾ || U+203E || ‾, ‾ |- | X̅x̅ (combining) || U+0305 || X̅ |- | Double overline(markup) | Xx || | style="font-size:75%" | text-decoration: overline; text-decoration-style: double; |- | Double overline(character) | X̿x̿ (combining) || U+033F || X̿ |- | rowspan="3" | Macron(character) | ¯ || U+00AF || ¯, ¯ |- | X̄x̄ (combining) || U+0304 || X̄ |- | X̄x̄ (precomposed) | colspan="2" style="background: #ececec; color: #2C2C2C; vertical-align: middle; text-align: center | varies |} An overline, overscore, or overbar, is a typographical feature of a horizontal line drawn immediately above the text. In old mathematical notation, an overline was called a vinculum, a notation for grouping symbols which is expressed in modern notation by parentheses, though it persists for symbols under a radical sign. The original use in Ancient Greek was to indicate compositions of Greek letters as Greek numerals. In Latin, it indicates Roman numerals multiplied by a thousand and it forms medieval abbreviations (sigla). Marking one or more words with a continuous line above the characters is sometimes called overstriking, though overstriking generally refers to printing one character on top of an already-printed character.

An overline, that is, a single line above a chunk of text, should not be confused with the macron, a diacritical mark placed above (or sometimes below) individual letters. The macron is narrower than the character box.