Capable of happening, existing, or being true without contradicting proven facts, laws, or circumstances:
The definition of feasible is that something is possible, doable or likely.
The definition of doable is something possible or something that can be done.
Usable for a specified purpose:
Able to reason
Not determined by reason; capricious; arbitrary; irrational.
(Informal) Used as an intensive:
Find another word for viable. In this page you can discover 20 synonyms, antonyms, idiomatic expressions, and related words for viable, like: workable, possible, applicable, within-reach, feasible, executable, doable, practicable, reasonable, unachievable and unreasonable.