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When greeting a stranger or an individual older than yourself, “hello” is rendered “yassas”: pronounced “ya-sAs.” If you’re greeting someone who you already know or saying hi to a child, “hello” is shifted to “yassoo”: pronounced “ya-sue.” “Yassoo” can also be spelled “yassou.”  Don’t worry too much about using the correct form of “hello.” Unlike other cultures (especially those which use Romance languages), the distinction is not important in Greek culture and native Greek speakers themselves use “yassas” and “yassoo” freely. “Yassas” can also be used to mean “goodbye” in Greek, so it’s a word you’ll hear frequently. For a more formal greeting, similarly to English, you’ll need to greet people depending on the time of day during which you’re introduced. These greetings can be spoken along with “yassas” (hello), or can be spoken on their own, just as in English we could greet someone by saying “hello” or by saying “good afternoon.”  “Good morning” is the preferred greeting until about 1:00 pm, and is said “Kalimera,”: pronounced “ka-lee-mer-ah.” “Good afternoon” is said “Kalispera,”: pronounced “ka-lee-speh-ra.” “Good evening” or “good night” is said “Kalinihxta,”: pronounced “ka-lee-nich-ta.” The informal word for “hi” in Greek is “ya” (pronounced “yaa”). This can be translated as “hello,” or “hi.” “Ya” can also be used as an informal goodbye, spoken between friends or from an adult to a child. To say goodbye to strangers or in a more formal setting, you’ll need to use the word “adío,” pronounced: “ah-dee-oh.”

Summary:
Say hello to strangers or friends. Give an appropriate greeting in the morning, evening, or night. Say “hi” informally.