Etymology

Noun

1. The twenty-third letter of Classical and Modern Greek and the twenty-fourth letter of Old and Ancient Greek.
2. A form of psychic energy.
   • 1993, Will Self, My Idea of Fun:

     ‘Come, lad,’ he said. ‘We will take tea together and speak of the noumenon, the psi and other more heterogenous phenomena.’

• Letter of the Greek alphabet: Ψ ψ
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