Formal:
* Noswaith dda i chi (pronounced: no-swah-th da ee khee) - This is the most formal way to say it, literally meaning "good evening to you".
Informal:
* Nos da (pronounced: nohs da) - This is the more informal way to say it, simply meaning "good night". You can also use this phrase for "good evening" as it is generally understood in context.
More Casual:
* Cael noson dda (pronounced: kyle no-son da) - This literally means "have a good night" and is a more casual way to say it.
To make it even more personal, you can add "" to the end of any of these phrases.**
For example, you could say:
* Noswaith dda i chi, ffrind (Good evening to you, friend)
* Nos da, cariad (Good night, love)
* Cael noson dda, fam (Have a good night, mom)