Meaning & use
xi
Last updated
Meanings
nouncountable
The fourteenth letter of the Greek alphabet, written as Ξ or ξ.
Grammar: Often written lowercase in math and science: the variable xi.
Patterns
- the Greek letter xi
The Greek letter xi looks like three horizontal lines joined by a vertical stroke.
In the equation, xi stands for an unknown constant.
The fraternity's name includes xi.
nouncountablephysicstechnical
A type of subatomic particle in physics, named after the letter, belonging to the baryon family.
Grammar: Usually capitalized when naming the particle: the Xi baryon.
Patterns
- the Xi particle
Physicists detected a rare xi particle in the experiment.
The xi baryon contains a strange quark.
A new xi was discovered at the collider.
nouncountable
A valid word in word games such as Scrabble, useful for scoring points because it uses the letter x.
Grammar: Accepted in Scrabble dictionaries; plural xis.
Patterns
- play xi
She scored well by playing xi on a triple-letter square.
Xi is a handy two-letter word when you hold an x.
He challenged xi, but the dictionary confirmed it.
Word forms
| plural | xis |
|---|
Common combinations
- the Greek letter xi
- The Greek letter xi appears in the formula.
- play xi
- Play xi to score points with your x tile.
- xi particle
- The xi particle decays quickly.
- xi baryon
- The xi baryon was discovered in the 1950s.
- lowercase xi
- A lowercase xi looks like a curly E.
Word family
- xis noun
- Plural of xi.
- xi baryon noun
- A particle in physics.
Commonly confused: xi or chi?
xi vs chi
Chi (X, χ) is the twenty-second Greek letter and looks like an English x, while xi (Ξ, ξ) is the fourteenth and has a different shape.
Practice
Which Greek letter is the fourteenth in the alphabet and also a valid Scrabble word?
Choose one answer.
Xi is the fourteenth Greek letter. Chi is the twenty-second, pi the sixteenth, and psi the twenty-third.
Make it your own
Write a sentence using “xi”, then check it and compare it with the examples above.