viable

In biology, viable also refers to the ability (or lack thereof) of an individual (plant, animal, etc.) or group of individuals to reproduce. In order to be a species, a pair of beings must be able to reproduce. (Thus, mules and hinnies are not a species.)

Viable also means having a reasonable chance of succeeding. ("A viable option") These days 'workable' is a more common way of saying the same thing.

Vi"a*ble (?), a. [F., from vie life, L. vita. See Vital.] Law

Capable of living; born alive and with such form and development of organs as to be capable of living; -- said of a newborn, or a prematurely born, infant.

⇒ Unless he [an infant] is born viable, he acquires no rights, and can not transmit them to his heirs, and is considered as if he had never been born. Bouvier.

© Webster 1913.