Definitionv1
Opportunity cost: the value of the best alternative you gave
Opportunity cost: the value of the best alternative you gave up by making a choice, specifically in attention terms measuring what you would have produced with that attention had you spent it on your most important work
Why This Is a Definition
This definition precisely establishes the semantic boundary of 'opportunity cost' in attention terms by specifying what it measures (value of best alternative) and providing a concrete operational definition for attention allocation (what you would have produced with attention spent on most important work).