“I was pleasantly surprised.”

You bought a cheap bottle of wine, but you actually liked it. You are telling your friend about this wine. You say:

I was pleasantly surprised.

pleasantly surprised

You can be "surprised" in both positive and negative ways. When you are surprised in a positive way, you can say that you were "pleasantly surprised".

The word "pleasant" means "good". So why do people say "pleasantly surprised" instead of "positively surprised" or "surprised in a good way"? This is an example of collocation: these words are just paired with each other.