Pareto Efficiency
Etymology
Named for Italian economist and sociologist Vilfredo Pareto, who developed the underlying ideas in the early 20th century; the term is eponymous. Pareto also lent his name to the separate “Pareto principle” (the 80/20 rule), which is a different idea entirely.
noun phrase · /puh-RAY-toh ih-FISH-un-see/
A state of allocation in which no one can be made better off without making someone else worse off.
What it names
A rigorous benchmark for “no waste left on the table” — and a reminder that an efficient outcome can still be deeply unfair, since it says nothing about how the pie is divided.
Example
The reform reached a Pareto-efficient allocation, yet critics noted it locked in a wildly unequal starting point.
Related idea
Do not confuse it with the Pareto principle, the observation that roughly 80 percent of effects come from 20 percent of causes; the two share a namesake but not a meaning.