dangerous

1 involving potential loss or injury the soldiers were specially selected to go on a dangerous mission behind enemy lines Synonyms grave, grievous, hazardous, jeopardizing, menacing, parlous, perilous, risky, serious, threatening, unhealthy, unsafe, venturesome Related Words dicey, insecure, precarious, treacherous, uncertain; ultrahazardous; chance, haphazard, random; distressing, sickening, unpleasant; ugly, wicked; adverse, bad, baleful, baneful, deleterious, detrimental, evil, harmful, hurtful, ill, inimical, injurious, malignant, nasty, noxious, pernicious, pestilent; deadly, deathly, destructive, dire, fatal, fateful, fell, killer, lethal, mortal, murderous Near Antonyms advantageous, beneficial, good; ultrasafe Antonyms harmless, innocent, innocuous, nonhazardous, nonthreatening, safe, unthreatening

2 causing or capable of causing harm the common knowledge that smoking is dangerous to one's health hasn't stopped some people Synonyms adverse, bad, baleful, baneful, damaging, harmful, deleterious, detrimental, evil, hurtful, ill, injurious, mischievous, nocuous, noxious, pernicious, prejudicial, wickedRelated Words hostile, inimical, unfriendly; contagious, deadly, infectious, infective, pestiferous, pestilent, pestilential, poisonous, venomous; insidious, menacing, ominous, sinister, threatening; hazardous, imperiling (or imperilling), jeopardizing, parlous, perilous, risky, unsafe, unsound; nasty, noisome, unhealthful, unhealthy, unwholesome; destructive, fatal, killer, lethal, malignant, ruinousNear Antonyms advantageous, beneficial, useful; favorable, good, propitious; curative, healthful, healthy, helpful, palliative, remedial, salubrious, salutary, wholesome; secure, sound; benignant; noncorrosive, nondestructive, nonfatal, noninfectious, nonlethal, nonpoisonous, nonpolluting, nontoxic, nonvenomousAntonyms anodyne, benign, harmless, hurtless, innocent, innocuous, inoffensive, safe