so long

interjection

, Informal.

1. goodbye:

   I said so long and left.

so long

sentence substitute

1. informal.
   farewell; goodbye

adverb

1. slang.
   for the time being; meanwhile

Word History and Origins

Origin of so long¹

An Americanism dating back to 1840–50

Idioms and Phrases

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]

Example Sentences

They’ve been waiting so long for the first and perhaps only time to be teammates this season.

From Los Angeles Times

It’s not so long since I thought I would not be around to mark that milestone.

From BBC

It is unclear why Russia took so long to respond to the operation, which saw Kyiv’s troops quickly gain control over a number of border communities.

From BBC

One-party rule is fine so long as the dominant party does what Madison expected.

From Salon

But she said there was discontent “that it took Biden so long to make a decision that could have saved lives” had it been taken earlier.

From BBC

Related Words

• goodbye
• send-off
• sendoff