What is the adjective form of arrive?

There isn't a single perfect adjective form of "arrive". However, depending on the context, you could use a few different options:

General arriving:

* Arrived: This is a past participle that can function as an adjective. Example: "The arrived guests were greeted warmly."

* Upcoming: This describes something that is going to arrive soon. Example: "The upcoming holiday season is exciting."

Specific situations:

* Late: If something arrives after the expected time. Example: "The train was late."

* Early: If something arrives before the expected time. Example: "The package arrived early."

* Unexpected: If something arrives without being anticipated. Example: "The unexpected visitor surprised us."

The best choice will depend on the specific meaning you want to convey.