1. goodbye.

So long, see you tomorrow.

If he didn't want to see her anymore, would he be able to tell her so long?

Usage notes: usually used in a friendly way

2. a very long time.

I haven't seen him in so long.

• sell someone a bill of goods
• sell someone down the river
• sell someone short
• sell something short
• sell soul
• sell soul to the devil
• sell your soul
• sell your soul to the devil
• send a message
• send around
• send around something
• send a signal
• send away for
• send away for something
• send away with a flea in ear
• send away with a flea in their ear
• send back
• send back someone
• send back something
• send chills down someone's spine
• send chills down spine
• send chills up someone's spine
• send chills up spine
• send flying
• send for