VIABILITY

'Viability' means in general "capacity for survival" and is more specifically used to mean a capacity for living, developing, or germinating under favorable conditions. The word is especially used in the following contexts:

★ pregnancy, viability refers to either:

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★ an early stage pregnancy that has a chance of reaching full-term and a live birth (as opposed to, for example, an ectopic pregnancy); or

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★ the shortest length of pregnancy after which a child born prematurely has a chance of survival. Generally, this ranges from 20-27 weeks.

★ environmental conservation, viability indicates the ability of a conservation target to persist for many generations or over long time periods.

★ experimental biology, ''viability'' of cells and tissues refers to the extent to which those cells and tissues are living.

★ natural selection, the fraction of individuals that survive to a given age.

★ economic development, viability indicates the ability of benefits to cover costs in development projects.