dan·ger·ous 
/ˈdeɪnʤərəs/ adjective
/ˈdeɪnʤərəs/ adjective [more dangerous; most dangerous] 1 : involving possible injury, harm, or death : characterized by danger
▪ Mining is dangerous [=hazardous] work. ▪ They complained to their boss about the dangerous [=unsafe] working conditions. ▪ She got into a car accident while driving through a dangerous intersection. ▪ He often drives at dangerous speeds. ▪ The city can be a dangerous place to live. ▪ dangerous neighborhoods — often + to ▪ Smoking is dangerous [=hazardous] to your health. 2 : able or likely to cause injury, pain, harm, etc.
▪ The storms may cause dangerous flooding. ▪ He is wanted for assault with a dangerous weapon. ▪ dangerous animals ▪ the most dangerous of drugs ▪ a dangerous enemy ▪ The police say that the man is armed and dangerous. [=he has a gun and he might try to shoot someone]
▪ Mining is dangerous [=hazardous] work. ▪ They complained to their boss about the dangerous [=unsafe] working conditions. ▪ She got into a car accident while driving through a dangerous intersection. ▪ He often drives at dangerous speeds. ▪ The city can be a dangerous place to live. ▪ dangerous neighborhoods — often + to ▪ Smoking is dangerous [=hazardous] to your health.
▪ The storms may cause dangerous flooding. ▪ He is wanted for assault with a dangerous weapon. ▪ dangerous animals ▪ the most dangerous of drugs ▪ a dangerous enemy ▪ The police say that the man is armed and dangerous. [=he has a gun and he might try to shoot someone]
dangerous ground/territory
: a situation in which you may do or say something that will have a bad result, make people angry, etc.
▪ As the conversation turned to politics, I knew we were heading into dangerous territory. ▪ You know you're treading on dangerous ground, don't you?
▪ As the conversation turned to politics, I knew we were heading into dangerous territory. ▪ You know you're treading on dangerous ground, don't you?
— dan·ger·ous·ly adverb
▪ She suddenly became dangerously ill. ▪ dangerously high levels of pollution ▪ They came dangerously close to being caught. ▪ He has always enjoyed living dangerously.
▪ She suddenly became dangerously ill. ▪ dangerously high levels of pollution ▪ They came dangerously close to being caught. ▪ He has always enjoyed living dangerously.
— dan·ger·ous·ness noun [noncount]
