Simply stated, an opportunity cost is the cost of a missed opportunity. It is the opposite of the benefit that would have been gained had an action, not taken, been taken—the missed opportunity.
Definitions and Examples of Opportunity Cost
Opportunity cost is the cost of a foregone alternative. If you chose one alternative over another, then the cost of choosing that alternative is an opportunity cost.
Opportunity Cost - The Economic Lowdown Podcast Series, Episode 1
Economists define an opportunity cost as the most highly valued opportunity given up when you make a choice.
Demand and supply
Economic Basics: Supply And Demand
In the context of supply and demand discussions, demand refers to the quantity of a good that is desired by buyers. Supply is defined as the total quantity of a product or service that the marketplace can offer.
Supply and Demand, Markets and Prices
So we have supply, which is how much of something you have, and demand, which is how much of something people want. Put the two together, and you have supply and demand.