noun
Uncommon
psi
pseye
Psi (noun) means the 23rd letter of the Greek alphabet (Ψ, ψ). Example: “Psi comes near the end of the Greek alphabet, just before omega.”
noun
1
The 23rd letter of the Greek alphabet (Ψ, ψ).
"Psi comes near the end of the Greek alphabet, just before omega."
2
In parapsychology, a supposed form of psychic or mental energy behind ESP and similar phenomena.
"The novel treats psi as a real, measurable force some characters can channel."
symbol
1
Abbreviation for "pounds per square inch," a unit of pressure.
"The tyre should be inflated to about 32 psi."
How to use psi
Learner’s notesIn plain EnglishEither the Greek letter, or (informally) mental/psychic energy, or the pressure unit "pounds per square inch."
Common mistake
Context decides the meaning — psi in a maths equation is the letter, psi in a tyre gauge is pressure, and psi in a sci-fi story is psychic power.
Common pairings
measured in psi
psi rating
psychic psi
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Word forms
- Plural
- psis
Fill the gap
Can you complete this real example?
_____ comes near the end of the Greek alphabet, just before omega.
Etymology
From the Greek letter name psi (Ψ), going back to Ancient Greek psei.
Synonyms
View more →
pounds per square inch
Frequently asked questions
What does “psi” mean?
The word “psi” means the 23rd letter of the Greek alphabet (Ψ, ψ). In plain terms, either the Greek letter, or (informally) mental/psychic energy, or the pressure unit "pounds per square inch.".
How do you pronounce “psi”?
“Psi” is pronounced pseye (/psaɪ/ in IPA).
How do you use “psi” in a sentence?
Here is “psi” used in a sentence: “Psi comes near the end of the Greek alphabet, just before omega.”
What part of speech is “psi”?
Depending on how it is used, “psi” can be a noun and a symbol.
Where does the word “psi” come from?
The word “psi” comes from Ancient Greek. From the Greek letter name psi (Ψ), going back to Ancient Greek psei.
Is “psi” a common word?
“Psi” is an uncommon word in modern English.
How many meanings does “psi” have?
“Psi” has 3 distinct senses listed in this dictionary. The most common is: the 23rd letter of the Greek alphabet (Ψ, ψ).
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