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Psi (ψ) | (/(p)saɪ/; uppercase Ψ, lowercase ψ) The 23rd letter of the Greek Alphabet with a numeric value of 700. In both Classical and Modern Greek, the letter indicates the combination /ps/ (as in English word "lapse").

The letter is most commonly used in quantum mechanics for wave functions like the ‘Schrödinger Equation’. May also be used to represent a position of a qubit in a quantum computer.
It is also used in the Polygamma Function where ‘Γ’ (z) is the gamma function.

Other notable appearances of ‘Psi’ include:
- Psychology/Psychiatry/Parapsychology (sometimes).
- Water Potential (Biology - Osmosis).
- Biochemistry: the rare nucleotide ‘Pseudouridine’.
- The gas giant ‘Neptune’ (eighth planet).
- The J/ψ meson, in particle physics.
- ‘Sai’ (weapon), the name of which is pronounced the same way - it also has the general shape of ψ.
- Stream function in fluid mechanics defining the curve to which the flow velocity is always tangent.

(note: some values may need citation)
“The letter ψ Psi is used to abbreviate Psychology. Don’t mix it up with Water Potential in Biology or ‘Wave-Functions’ for Quantum Mechanics...”
Ψ by Omega’s Last December 28, 2019
Words you can keep
Simbles of the folk nation gang it mean that u live life as folk nation and will ride on any opposeing forces. curry boy
A 6 point star representing folk all sets under the number 6 representing ψ.
ψ by pitch fork simble October 12, 2008
RUN FOR YOUR LIVES THERE ARE PEOPLE WITH ΨS CHASING US!!! DDD:
Ψ by CarkyAmster February 23, 2023
KKΨ The letter abbreviation for National Honorary Fraternity: Kappa Kappa Psi, which is for college band members that promotes the existence and welfare of the college and university bands.
"Hey, what fraternity are you in?"
"I'm in KKΨ. Yea, I said it. I'm a band bitch."
kkΨ by @tight_and_bright September 24, 2014

( ͡°▽ ͡°)Ψ 

Hey do you know ( ͡°▽ ͡°)Ψ from lol pics?

ψύξης όπως ένα πουλί 

ψύξης όπως ένα πουλί
More from Urban Dictionary

age gate 

An absolutely foolproof way to keep minors from viewing content deemed "too mature" for them to watch.
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Bill: "Fucking age gate! *quick scroll* THERE! I was born on January 1, 1904. Fuck you age gate."
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board chow 

A)
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B)
Can also be used to gross out Non-Techie people
A)
Bill: want to go to the club?
Bob: No, I've got to clean out my board chow, keys are starting to stick.

B)
Bill: Want to go out to get a bite?
Bob: No, i am just going to have some of my board chow/
Bill: Whats' that?
Bob: The food scraps that collect in my keyboard; Want some?
Bill: *GAG* *HURL* *GAG*
board chow by BinaryHackerMan September 3, 2007
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young pup 

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Ah, you're just a young pup at 23!
young pup by the dog May 30, 2006
Word of the Day on August 25, 2026
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Some grebo passed with Sabbath playing on his stereo.
The Poppies are at no. 17? God, a grebo band in the charts!
They're playing nu-metal now, bloody grebos!
grebo by cactuscat September 15, 2006
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