Psi is the 23rd letter of the Greek alphabet and is commonly used in various contexts such as mathematics, physics, and psychology. Its numerical value in the Greek numeral system is 700. In psychology, psi is sometimes used to represent parapsychological phenomena or psychic abilities.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Letter before omega. Explanations are generated by AI and may be inaccurate.