Scarcity

n. rareness, scarceness, state of being in short supply

In economics, scarcity is defined as the condition of  human wants and needs exceeding production possibilities. In other words, society does not have sufficient productive resources to fulfill those wants and needs. Alternatively, scarcity implies that not all of society's goals can be fully attained at the same time, so that trade-offs are made of one good against others. In an influential 1932 essay, Lionel Robbins  defined economics as "the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses."
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Noun
1. a small and inadequate amount
(synonym) scarceness
(antonym) abundance, copiousness, teemingness
(hypernym) insufficiency, inadequacy, deficiency
(hyponym) dearth, paucity

(n.)
The quality or condition of being scarce; smallness of quantity in proportion to the wants or demands; deficiency; lack of plenty; short supply; penury; as, a scarcity of grain; a great scarcity of beauties.
  

A condition where there is less of something available than at least some people would like to have if they could have them at no cost to themselves. Note that this technical economic definition of "scarcity" differs greatly from the notion of scarcity as "unusual rarity" that predominates in most ordinary language. (For example, automobiles are not currently "scarce" in Los Angeles in the sense of being rare or unusual to see, but they are definitely "scarce" in the economic sense because many Angelenos would certainly take more of them if they were being given away for free.) Because the total quantity of goods and services that people would like to have always far exceeds the amount which available economic resources are capable of producing in all known human societies, people as individuals and/or as members of larger social units must constantly be making choices about which desires to satisfy first and which to leave less than fully satisfied for the time being. That is, they must constantly decide how best to allocate (apportion or distribute) the scarce resources available to them among the various alternative uses to which they can be put. Thus scarcity is the fundamental condition that gives rise to the patterns of choosing behavior whose study constitutes the main focus of the academic discipline of economics. [See also: optimum, marginal analysis, allocation, economics]