Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • 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 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 of psi

probably by shortening & alteration from psychic


First Known Use: 1942


3

psi

abbreviation

Definition of psi

  1. pounds per square inch




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

February 11, 2016

the holder of an office

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image33683556

How much does a batman (the Turkish unit of measurement) weigh?

2.2 pounds 196.5 pounds 100 pounds 16.96 pounds
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ