follow Dictionary.com

Slideshow
Hasta la Vista! 8 Goodbyes Worth Borrowing
goodbye
[good-bahy]

Have you ever thought about the phrases we've borrowed from other languages to say see you later? Sometimes it's for flair, or familiarity. But most of the time, the choice is effortless—these words are as equally English as any other words that make it into the dictionary.

The parting expression goodbye has been used in English since the 16th century, but it was originally a contraction of the phrase God be with ye. The religious connotations have long since fallen away, and etymologists believe that good replaced god in this phrase thanks to the influence of terms like good day and good night.

sayonara
[sahy-uh-nahr-uh]
Sayonara comes to English from the Japanese meaning "goodbye," or literally, "if it is to be that way." It first crossed over into English in the late 19th century, and was often associated with travelers, both military and civilian. This term experienced a peak in usage in the 1950s and 1960s, propelled by appearances in pop culture, like the 1957 Marlon Brando film Sayonara, which was based on a 1954 novel.
adieu
[uh-doo, uh-dyoo]
Adieu entered English when Middle English was still spoken, back in the 14th century. Much like goodbye, this farewell has religious origins; it comes from the Middle French meaning “to God.” This ultimately comes from a longer expression in Old French va a deu meaning “go to God.”
adios
[ad-ee-ohs, ah-dee-]
English borrowed adieu from French in the Middle Ages and adios from Spanish in the early modern period. Like its French counterpart, this term means “to god,” though it's spoken today without religious implications.
auf-wiedersehen
[ouf vee-duhr-zey-uhn]
Auf Wiedersehen is an expression of goodbye that comes from the German meaning "until we meet again," or more literally, "on seeing again." It entered the English language in the 19th century and peaked in English usage in the late 1930s, no doubt thanks to World War II.
ciao
[chah-aw]
Ciao comes from the Italian dialectal term schiavo which means "(I am your) slave," or more colloquially "your humble servant." It ultimately finds its roots in the medieval Latin sclavus meaning "slave."
farewell
[fair-wel]
The expression farewell dates from Middle English, though back then it was sometimes spelled farwel. When it first entered English, speakers bid farewell to friends starting out on a journey, but after time, it took on the more general sense of a parting goodbye.
hasta-la-vista
[ahs-tah lah vees-tah]
Hasta la vista comes from the Spanish for “until we meet” or, more literally, “until the sighting.” Though it's been in the English lexicon since the early part of the 20th century, this goodbye gained popularity in the 1990s with the help Arnold Schwarzenegger as the leading cyborg in Terminator 2: Judgment Day (so no judgement here if you thought it was supposed to be said with an Austrian-American accent).