What is the synonym for good evening?

There isn't really a single perfect synonym for "good evening" that captures its exact meaning. It depends on the context and the tone you want to convey. Here are some options, each with slightly different nuances:

Formal:

* Greetings

* Evening

* Good night (used later in the evening)

Informal:

* Hey there

* Howdy

* What's up?

* Evening

More specific:

* Good night to you

* Have a good evening

* I hope you have a pleasant evening

You could also use more creative phrases like:

* Wishing you a restful evening

* May your evening be filled with joy

* Enjoy the rest of your evening

Ultimately, the best synonym will depend on the specific situation and the relationship between the speaker and listener.