noun

• 1The fourteenth letter of the Greek alphabet (Ξ, ξ), transliterated as ‘x’.

  ‘This page displays the Greek alphabet and gives information on pronunciation for both ... y as in yet, and before gamma, kappa, xi, or chi.’

  More example sentences

  • ‘While having no Latin derivative, the Xi was adopted into the early Cyrillic alphabet, as the letter ksi.’

  1. 1.1Astronomy followed by Latin genitive The fourteenth star in a specified constellation.
     ‘Xi Cygni’
     More example sentences

     • ‘The highlight for me that night was Xi Bootes. This colorful double lies about 8 degrees east of Arcturus.’