Ksi

An example of the use of Ksi after it was formally abolished: a civil census 1782 (GATO, f. 389, cat. 1, case 2, p. 146): Жена Аѯинья Семенова дочь — 30… Ksi (Ѯ, ѯ italics: Ѯ ѯ) is a letter of the Cyrillic script. It is a letter of the early Cyrillic alphabet, derived from the Greek letter Xi (Ξ, ξ). It was mainly used in Greek loanwords, especially words relating to the Church.

Unlike other eliminated letters such as Omega and Yus, Ksi was a later borrowing from Greek and does not appear in any form in the Glagolitic script, which was used until the Middle Ages.