From Longman Dictionary of Contemporary Englishdangerousdan‧ger‧ous /ˈdeɪndʒərəs/ ●●● S2 W2 adjective 1 DANGEROUSable or likely to harm or kill you → harmful laws about dangerous dogs Some of these prisoners are extremely dangerous.highly/very dangerous It was a highly dangerous situation.dangerous for The crumbling sidewalks are dangerous for old people.dangerous to The virus is probably not dangerous to humans.it is dangerous for somebody to do something It’s dangerous for a woman to walk alone at night. The powdered milk was not as good as breast milk, and was downright dangerous (=actually dangerous) when it was mixed with unclean water.2 RISKinvolving a lot of risk, or likely to cause problems SYN risky The business is in a dangerous financial position. a politically dangerous strategy3 → dangerous ground/territoryTHESAURUSdangerous likely to cause death or serious harm, or cause something bad to happenSnow and ice are making driving conditions very dangerous.dangerous drugsa dangerous criminalrisky if something is risky, something bad could easily happen or you could easily make a mistakeDoctors said it was too risky to operate.a risky situationhazardous /ˈhæzədəs $ -zər-/ especially written dangerous – used especially about substances, jobs, and journeyshazardous wastehazardous chemicals hazardous occupationsThe expedition was extremely hazardous.unsafe dangerous because someone is very likely to be hurt – used especially about places or conditionsThe roads are unsafe for cyclists.unsafe working conditionstreacherous /ˈtretʃərəs/ formal or literary places or conditions that are treacherous are very dangerous for anyone who is walking, driving, climbing etc in themThe snow turned to ice, making conditions treacherous for walkers. the island’s treacherous coastlineWith no lighting, the roads can be treacherous.perilous /ˈperələs/ literary a perilous journey, situation etc is very dangerousa perilous journey across the seahigh-risk [only before noun] a high-risk job, situation, or behaviour is likely to be dangerousDrug users need to know that sharing needles is high-risk behaviour.
Examples from the Corpusdangerous• Now the surface was so slack that it was becoming dangerous.• Today the judge dismissed reports from two psychiatrists who said they did not believe Bourgois was dangerous.• Working conditions for adults, who earned about $ 3 a day, were also dangerous.• Neil thought the man looked dangerous.• Police described the three escaped prisoners as highly dangerous.• Snow and ice are making driving conditions very dangerous.• He was cowardly and dangerous, and obviously very good at his job.• Women felt that complaining about sexual harrassment was dangerous, as there was always the threat of losing their jobs.• Not a dangerous disposition I think; though it might be if my nature were more masculine & daring.• a dangerous dog• dangerous drugs such as heroin and crack• It's too dangerous for the kids to play in the street.• At least the man was wise enough to know how dangerous he was.• a dangerous neighborhood• Using humor in a job interview is a dangerous thing - you never know how the interviewer will react.• It is dangerous to assume that share prices will continue to rise.• Air bags are exceedingly fast, which can be dangerous to infants and elderly passengers.• The pilot says it's too dangerous to try to land the plane in this weather.• It is either tautologous, positively dangerous, unoriginal or highly ambiguous.• It's dangerous work but for men like Clement, summer firefighting is an important source of income.dangerous to• The paint they're using is dangerous to people and animals.