perilous

dangerous, hazardous, precarious, perilous, risky mean bringing or involving the chance of loss or injury. dangerous applies to something that may cause harm or loss unless dealt with carefully <soldiers on a dangerous mission>. hazardous implies great and continuous risk of harm or failure <claims that smoking is hazardous to your health>. precarious suggests both insecurity and uncertainty <earned a precarious living by gambling>. perilous strongly implies the immediacy of danger <perilous mountain roads>. risky often applies to a known and accepted danger <shied away from risky investments>.