Viable means capable of working successfully or able to survive and grow. When scientists test whether a seed is viable, they're checking if it can actually sprout and grow into a healthy plant. When a business owner considers whether an idea is viable, she's asking: “Can this actually work and succeed?”

You'll often hear people discuss whether a plan is viable. If your class wants to raise money for a field trip by selling lemonade, you'd need to figure out if that's a viable plan: Do you have enough time? Will enough people buy it? Can you make enough profit? A plan might sound exciting but still not be viable if the practical obstacles are too great.

The opposite of viable is unviable: something that cannot work or survive. A business plan might be unviable if it costs more money than it could possibly earn. An Antarctic expedition in winter might be unviable because the conditions are simply too dangerous. When something is viable, it has a real chance of success.