◌̅

◌̅	U+0305, ̅ COMBINING OVERLINE

‾	U+203E, ‾ OVERLINE

See also: ◌̿, ◌̲, and ◌̳

Translingual

A horizontal line to be placed above letters and digits. It connects to itself on either side if it's also placed over those letters.

◌̅

Used in some languages to mark abbreviations.
Ι̅Σ̅ Χ̅Σ̅, a Greek abbreviation of Jesus Christ.

◌̅ (English name overbar or overline or overscore or vinculum)

(mathematics) Drawn over repeating digits.
12 ÷ 7 = 1.7̅1̅4̅2̅8̅5̅ = 1.714285714285714285...
(geometry) Drawn over letters which represent a line segment.
segment A̅B̅ has the same length as segment C̅D̅
(physics) Used to denote antiparticles.
p (proton); p̅ (antiproton)
(mathematics) Indicates the complex conjugate of a complex number.
z̅ = x̅+̅i̅y̅ = x−iy
(statistics) Used to mark the mean of a sample.
X̅ (sense 6) used for ten thousand as the logo of the Long Now Foundation
(Roman numerals) Multiplies the value of a group of digits by one thousand.
IV — four; I̅V̅ — four thousand; I̿V̿ — four million
- 2019 April, Evander Lewis Price, “[The Clock of the Long Now] Conclusions: The Interval”, in Future Momentality‎^[1] (in English), Cambridge, Mass.: Harvard University, page 173:
  Their [the Long Now Foundation’s] logo—you can’t miss it—is the decem milia, the monolithic (and chronolithic) Roman numeral for ten thousand. X marks the clock: X̄
(Greek numerals) In Byzantine Greek and in Coptic, converts a letter into a digit. E.g. κ̅ (modern κʹ) '20'.
(phonetics) marks a string of syllables or segments with high pitch. Compare ˹ ... ˺.
(actuarial notation) Used to indicate continuous payments.
$a̅ n̅|$ ― n-year annuity payable continuously