If an activity or action is risky, it is dangerous or likely to fail. Investing in airlines is a very risky business. It's risky to assume that we know what voters will be thinking in a year's time.
Synonyms: dangerous, unsafe, precarious, hazardous, insecure, more... Collocations: a risky [investment, asset], the [investment] has become too risky, is a risky business, more...