Definition
Viable means capable of living — literally, from the French vie, 'life'. A viable seed can germinate; a viable business can sustain itself; a viable plan can actually be carried out. The word draws a hard line between ideas that merely sound good and those that can survive contact with reality: many proposals are attractive, fewer are viable. In biology and medicine it keeps its literal sense of 'able to survive'.
Examples
- Solar power is now a commercially viable alternative to coal in much of the world.
- The committee concluded that the proposal, while imaginative, was not financially viable.
- Seeds stored in the vault remain viable for decades.
Synonyms
feasible · workable · practicable · sustainable · achievable
In TOEFL & IELTS
Indispensable for IELTS Writing Task 2 solution paragraphs: 'a viable alternative/solution/option' is among the strongest collocations you can deploy. TOEFL passages use it in both senses — economic viability of technologies and biological viability of organisms — so read the context. The noun is 'viability'; the antonym 'unviable' (or 'non-viable' in biology).