psi

The twenty-third letter of Classical and Modern Greek and the twenty-fifth letter of Old and Ancient Greek.countable

A form of psychic energy.uncountable

• When an event is classified as a psi phenomenon, it is claimed that all known channels for the apparent interaction have been eliminated.

Pound per square inch (an imperial unit of pressure)

• For M2, this is typically around 3250 MPa (471,000 psi) when tempered at 300°F (149°C).