psi

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

2. (uncountable, parapsychology, science fiction) A form of psychic energy.Examples: "‘Come, lad,’ he said. ‘We will take tea together and speak of the noumenon, the psi and other more heterogenous phenomena.’"; "When an event is classified as a psi phenomenon, it is claimed that all known channels for the apparent interaction have been eliminated."; "It traces the growth of homo gestalt with the uniting of six lovely outcasts of society who have psi powers and come together as a hive mind, thus creating a gestalt super-being."uncountable