khi

plural khis

1. alternativeAlternative spelling of chi (uppercase Χ, lowercase χ), the 22nd letter of the Greek alphabet.

   The letters upsilon, phi, khi, psi, δ were Greek additions

   1963, Thomas Albert Sebeok, Current Trends in Linguistics, Mouton, page 404

   2 more examples

   It is known, from the existence in his time¹ of the Delphic tripod, that all these letters existed in 480 B.C. ; but on that monument the Khi and Psi differ from the forms used later.

   1898, Claude Reignier Conder, The Hittites and Their Language, W. Blackwood and Sons, page 249

   Greek scripts display notable local characteristics — principally with regard to the shape of letters but also in the matter of the phonetic values attributed to signs such as san, sigma, khi, and psi.

   2006, Jonathan M. Hall, A History of the Archaic Greek World, Blackwell Publishing, page 57