so long

American  

interjection

Informal.

1. goodbye.

   I said so long and left.

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so long British  

1. informal farewell; goodbye

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adverb

1. slang for the time being; meanwhile

so long Idioms  

1. Good-bye, as in So long, we'll see you next week. The allusion here is puzzling; long presumably means “a long time” and perhaps the sense is “until we meet again after a long time,” but the usage has no such implication. [Colloquial; first half of 1800s]

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Etymology

Origin of so long

An Americanism dating back to 1840–50

Example Sentences

See Examples For:

so long

One reason the mystery endured for so long was simply the rarity of inherited AnWj negative blood.

From Science Daily ● Sep. 19, 2026

None, I’d argue — so long as that filmmaker can present either side of said debate with as much tact as the other.

From Salon ● Sep. 19, 2026

You’d want to underweight stocks so long as you believe interest rates will continue rising, but overweight them once you think that a rate-cut cycle is about to begin.

From MarketWatch ● Sep. 18, 2026

Much like a restaurant franchisee, developers in return can brand their projects as a Trump tower, so long as it conforms to various design and service standards.

From The Wall Street Journal ● Sep. 13, 2026

You can only keep people at arm’s length for so long.

From "Bye Forever, I Guess" by Jodi Meadows

Related Words

• goodbye
• send-off
• sendoff