Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun psi

2 senses of psi

Sense 1
pounds per square inch, psi -- (a unit of pressure)
       => pressure unit -- (a unit measuring force per unit area)

Sense 2
psi -- (the 23rd letter of the Greek alphabet)
       => letter, letter of the alphabet, alphabetic character -- (the conventional characters of the alphabet used to represent speech; "his grandmother taught him his letters")