* τελετή (telētē): This is probably the closest single word and is often used for a ritualistic ceremony, especially one with religious or mystical significance.
* εορτή (eortē): This refers to a festival or celebration, often with religious connotations. It might be suitable if the ceremony is celebratory in nature.
* λειτουργία (leitourgia): This means "liturgy" or "public service," and is appropriate for ceremonies that are part of a religious service.
* ακολουθία (akolouthia): Similar to λειτουργία, this word refers to a sequence of liturgical rites or a service.
* τελετουργία (teletourgía): This is a more formal word that combines elements of τελετή and εργασία (work) and could be used for a complex and formal ceremony.
To choose the best word, you need to consider the context. For example, a wedding ceremony might be best described as a τελετή or an εορτή, while a religious service would be a λειτουργία or ακολουθία.