Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary
1

psi

play
noun \ˈsī, ˈpsī\

Definition of psi

  1. :  the 23d letter of the Greek alphabet — see alphabet table



Origin and Etymology of psi

Middle English, from Medieval Latin, from Late Greek, from Greek psei


First Known Use: 15th century

Rhymes with psi


2

psi

play
noun \ˈsī\

Definition of psi

  1. :  parapsychological psychic phenomena or powers



Origin and Etymology of psi

probably by shortening & alteration from psychic


First Known Use: 1942


3

psi

abbreviation

Definition of psi

  1. pounds per square inch




Medical Dictionary

1

psi

play
adjective \ˈsī\

Medical Definition of psi

  1. :  relating to, concerned with, or being parapsychological psychic events or powers <psi phenomena>




2

psi

noun

Medical Definition of psi

  1. :  psi events or phenomena




Learn More about psi

  1. Medical Dictionary: Definition of psi


Seen and Heard

What made you want to look up psi? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

to criticize in a loud and angry way

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

confounded-person

Which is a synonym of indolent?

melancholy philistine lazy frenetic
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ