So long! means bye, take care. It's an informal goodbye: you wave, leave, or end a conversation. So long, Nina! Enjoy the rest of your trip. It sounds friendly and a little old-fashioned. Long isn't about time here: the phrase says nothing about how long you'll be apart.
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So long! / So long, + person's name
- So long, Nina! Enjoy the rest of your trip.
- He waved from the bus and called, "So long!"
- We said so long to our neighbours before leaving the island.
What changed
First versionThank you for the interview. So long, Mr Grant.
RevisionThank you for the interview. Goodbye, Mr Grant.
So long looks like just another goodbye, so people use it anywhere. But it's an informal, friendly farewell. After an interview or in a business email it sounds too casual; there, say Goodbye or write Best regards.
So long as is something else entirely: 'on condition that'. You can borrow it so long as you return it. For so long means 'for such a long time': Why did you wait for so long? Add one word, and the goodbye disappears.
Your turn
The visitor waved and said, "So long!" What did he mean?
Show the answer
Goodbye! — The visitor is waving, so it's a farewell: Goodbye! A complaint about waiting would be said differently: That took so long!
Say goodbye to a friend after meeting at a café in one sentence with so long.
So long, Ben — see you at the match on Saturday!
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