Psi (Ѱ, ѱ; italics: Ѱ ѱ) is a letter in the early Cyrillic alphabet, derived from the Greek letter psi (Ψ, ψ). It represents the sound /ps/, as in English naps. According to the school rules developed in the 16th and the 17th centuries, such as Meletius Smotrytsky's grammar book, it was intended for use in words of Greek origin, but it was occasionally used for writing native words as well like Ukrainian ѱы (psy, "dogs"). It was used especially in words relating to the Eastern Orthodox Chu…