Definitions

1. noun

A line or marking placed above a letter or other character in a font, indicating that it should be used as a symbol rather than a letter.

“The overline above the letter ‘A’ indicates that it should be used as a symbol for a special chemical formula.”

2. verb

To place a line above a letter or other character in a font, indicating that it should be used as a symbol rather than a letter.

“The typesetter overlined the letter ‘A’ to indicate its use as a symbol in the chemical formula.”