casual: 안녕 · formal: 안녕하십니까
hello, hi; how are you?
Example
선생님, 안녕하세요? 오늘 날씨가 좋네요.
Hello, teacher! The weather is nice today.
Word parts
안 peace+녕 peace
Literally 'Are you at peace?' — the everyday polite hello.
Good to know
Works any time of day — morning, afternoon or evening. A slight bow while saying it is polite.