interjection
A formal or polite way to say goodbye, often used when parting for a longer time or in more solemn situations. In casual speech, shorter forms like さよなら or じゃあね are more common.
See also: さよなら
先生に「さようなら」と言って教室を出た。
I said goodbye to the teacher and left the classroom.
さようなら、また会う日まで。
Farewell, until we meet again.