When something is viable, it has the ability to grow or function properly. A viable seed can develop into a plant, while a viable company has the resources to succeed.
The adjective viable refers to something able to function properly and even grow. It is made up of the Latin roots vita which means "life," and the ending -able which means "to be possible." In terms of science or botany, when a plant is viable it can live and flourish in an environment such as a cactus in the desert. Consider also the Wright brothers, who were the first to develop a viable airplane after many tries and spectacular failures.