This is a linkpost for https://atheistkit.wordpress.com/ethics/
Clarification please. How do you avoid this supposed vacuity applying to basically all definitions? Taking a quick definition from a Google Search: A: "I define a cat as a small domesticated carnivorous mammal with soft fur, a short snout, and retractile claws." B: "Yes, but is that a cat?"
Which could eventually lead back to A saying that:
A: "Yes you've said all these things, but it basically comes back to the claim a cat is a cat."
Definitions are at best a record of usage. Usage can be broadened to include social practices such as reward and punishment. And the jails are full of people who commit theft (selfishness) , rape (ditto), etc. And the medals and plaudits go to the brave (altruism), the generous (ditto), etc.