In spanish we say "Adiós", but in Argentina we say more "Chau"

In America we say "Goodbye" lol... in Mandarin Chinese it is 再见, which is pronounced zai tian (Pinyin Zai Jian)

in chinese we say :再见

خداحافظ Khoda hafez .............. it mean god protect you from any bad things ;)

In Thailand we say "ลาก่อน" but it quite formal and similarly we will don't meet again. Usually we also use "bye" same as american or use "ต้องไปแล้ว(Thong pai laew) / ไปล่ะ (pai la) <informal>