Xi — ξ Greek Letter Symbol
ξ
Xi — ξ / Ξ
14th letter of the Greek alphabet · pronounced /zaɪ/ or /ksaɪ/
MathematicsPhysicsEngineering
Copy symbol
ξ
Lowercase xi
Ξ
Uppercase Xi
Technical reference
| Unicode (lowercase) | U+03BE |
| Unicode (uppercase) | U+039E |
| HTML entity | ξ |
| HTML decimal | ξ |
| LaTeX | \xi |
| Python / Unicode escape | \u03be |
| Alt code (Windows) | Alt + 958 |
Uses in science & engineering
Damping ratio (alternative)
Used as an alternative to ζ for the damping ratio in some engineering texts.
\(\xi = \frac{c}{c_{cr}}\)
Random variable
Denotes a random variable in probability theory and statistical mechanics.
\(P(\xi \leq x) = F(x)\)
Xi baryon (particle physics)
Symbol for the xi baryon, a type of subatomic particle containing strange quarks.
\(\Xi^0, \Xi^-\)
Generalised coordinate
Used in Lagrangian mechanics as a generalised coordinate for complex systems.
\(\frac{d}{dt}\frac{\partial L}{\partial \dot{\xi}} = \frac{\partial L}{\partial \xi}\)
Related symbols
How to insert in applications
Windows
Best option: copy from this page.
Or press Win + . to open emoji & symbols panel.
Alt codes work only in Word/Notepad with NumLock on and English layout — not in browsers.
Or press Win + . to open emoji & symbols panel.
Alt codes work only in Word/Notepad with NumLock on and English layout — not in browsers.
macOS
Press ⌃⌘Space → Character Viewer → search “xi”
Microsoft Word
Type 03be then press Alt+X
Google Docs
Insert → Special characters → search by name
Excel
Insert → Symbol → Subset: Greek → select symbol
LaTeX
Use in math mode: $ … $
Python
Use Unicode escape or chr()
HTML / CSS
Use HTML entity or decimal code