The benefit that is sacrificed by choosing one course of action rather than the next best alternative, e.g. the opportunity cost sacrificed in building a road might be the use of the land for farming.
glossary
Best or most favorable, esp. under a particular set of circumstances.
1. The most favorable conditions. 2. The best or most favorable situation. 3. The best possible compromise between two opposing positions, tendencies, etc.
A type of derivative security that gives the buyer the right, but not the obligation, to buy or sell an asset at a set price on or before a given date.