2.  Physiology .
     a.  physically fitted to live.
     b.  (of a fetus) having reached such a stage of development as to be capable of living, under normal conditions, outside the uterus. 

 

3.  Botany . able to live and grow.

 

4.  vivid; real; stimulating, as to the intellect, imagination, or senses: a period of history that few teachers can make viable for students.

 

5.  practicable; workable: a viable alternative.

 

6.  having the ability to grow, expand, develop, etc.: a new and viable country.