The Ctistae (Greek: κτίσται) were a group/class in ancient Thracian culture. They led celibate lives, never marrying. They were held in a place of honor by the Thracians, with their lives being dedicated to the gods.
The Bulgarian word чисти (chisti) can be used to explain the name of this ancient Thracian group. "chist" means clean/pure, and "chisti" is the plural form of the word, just like "ctistae" is the plural form of "ctist". It is possible that the letters ct (κτ) are simply a way of writing down the "ch" sound, not present in the ancient Greek alphabet.
^Strabo, History VII.3.3: and there are some of the Thracians who live apart from woman-kind; these are called "Ctistae," and because of the honour in which they are held, have been dedicated to the gods and live with freedom from every fear; accordingly, Homer speaks collectively of all these peoples as "proud Hippemolgi, Galactophagi and Abii, men most just," but he calls them "Abii" more especially for this reason, that they live apart from women, since he thinks that a life which is bereft of woman is only half-complete