river bed (river beds plural) , riverbed A river bed is the ground which a river flows over. n-count. up-river, upriver. Something that is moving up-river is moving towards the source of a river, from a point down the river.
In economics, the term trade-off is often expressed as an opportunity cost, which is the most preferred possible alternative. A trade-off involves a sacrifice that must be made to get a certain product or experience. A person gives up the opportunity to buy 'good B,' because they want to buy 'good A' instead.
trade. n. 1. (Commerce) the act or an instance of buying and selling goods and services either on the domestic (wholesale and retail) markets or on the international (import, export, and entrepot) entrepÃ´t. markets. (2) crafts a personal, occupation esp a craft requiring. skill