Within the context of philosophy utility, especially for utilitarians, is not usefulness, it's happiness. It's called utility because it's useful towards the end of happiness.
So "utility" is both "happiness" and "something that's useful towards the end of happiness". In other words, it's both the end and the means towards it at the same time? But that makes no sense. That's like saying the act of driving a car is both "getting someplace" and the means towards it. Not only that, but Utility is also various things that aren't at all related to how the word is commonly understood. This is like me defining a strawberry as something that could be an apple, an orange, or perhaps a coconut. To be fair, the quoted definition has a common theme. The various definitions are all positive things. But on the other hand, my example is just as good, because the various definitions are all delicious fruits!"Utility is defined in various ways, including as pleasure, economic well-being and the lack of suffering."
>So "utility" is both "happiness" and "something that's useful towards the end of happiness". No. Utility is the usefulness in achieving the end. And the end is happiness. And achieving the end well is aggregating a lot of happiness. Therefore high utility is high happiness. For that reason philosophers equate utility with happiness. It's a definition specific to philosophy. Hopefully that clears things up.
You're still equating it with both the end and the means towards it. In other words, you're still not making sense.
Here's what you originally said: But now you're saying.. something different that I can't be bothered to parse right now. I give up.utility, especially for utilitarians, is not usefulness, it's happiness. It's called utility because it's useful towards the end of happiness