Greetings in Greek are time-sensitive, so whether you are saying hello or goodbye, you need to know the right phrase for the right time of day.
Kali Means Good
Whether it is morning, evening or nighttime, all of the greetings begin with " kali," which generally means "good." Goodnight in Greek is kalinikta, pronounced KA-lee-NEEK-ta, while good morning is kalimera, and kalispe ra means good evening.
Kalispera is used earlier in the evening, as a greeting. You generally would only say kalinikta late at night, when it is likely that the person you are saying farewell to is going straight to bed, not on to another bouzouki club or taverna. For example, after finishing dinner at a restaurant, you should say "kalispera," or "good evening," and not "kalinikta," which means "good night."
Nikta Means Night
"Nikta" is not that far off from the Greek word for night, nuxta. In Greek, the word for night also calls to mind the Greek goddess of the night, Nyx. The alternate spelling of "nixta" preserves the name of this deity more clearly.
Alternative Words and Spellings
Another much more rare way to say"goodnight" is "kali oneiros" or "oneira glyka," meaning "good dreams to you," which is Όνειρα γλυκά in Greek letters. Oneira glyka literally means sweet dreams.
As a general note, there is no absolutely official transliteration between Greek and English, so there are many spelling variants which are acceptable.
Alternate spellings for kalinikta are kali nicta, kalinicta, kali nikta, kali nixta. Common misspellings are kali nichta, calinicta, cali nicta, cali nikta, calinichta.