Synonyms and antonyms of Dangerous or harmful in British Thesaurus

dangerous (adjective)

likely to harm or kill someone, or to damage or destroy something

harmful (adjective)

causing harm

disastrous (adjective)

causing a lot of damage or harm

damaging (adjective)

causing physical harm to something so that it is broken, spoiled, or injured

risky (adjective)

involving the possibility of danger, harm, or failure

hazardous (adjective)

dangerous, especially to people’s health or safety

unsafe (adjective)

dangerous

ruinous (adjective)

causing severe damage or loss

perilous (adjective)

mainly literary very dangerous

injurious (adjective)

formal causing harm or damage

adverse (adjective)

negative, unpleasant, or harmful

at your peril (mainly literary)

mainly literary used for saying that doing something is dangerous or could cause serious problems

calamitous (adjective)

formal causing serious damage, or causing a lot of people to suffer

cataclysmic (adjective)

changing a situation in a sudden, violent, and unpleasant way

catastrophic (adjective)

causing a lot of damage, or making a lot of people suffer

combustible (adjective)

likely to suddenly become dangerous or violent

convulsive (adjective)

mainly journalism causing major problems or serious harm

damaging (adjective)

having a negative effect on someone or something

dangerous (adjective)

likely to have a bad effect or to cause a problem

dangerously (adverb)

to such a degree that harm, death, damage, or destruction is possible

dangerously (adverb)

in a way that is likely to harm someone or to damage something

dark (adjective)

morally bad, dangerous, or frightening

deadly (adjective)

able or likely to kill people

deleterious (adjective)

very formal harmful

destructive (adjective)

causing severe damage or harm

detrimental (adjective)

harmful or damaging

devastating (adjective)

causing a lot of harm or damage

dicey (adjective)

informal involving danger or risk

dodgy (adjective)

Britishinformal dangerous or not certain

dubious (adjective)

not completely good, safe, or honest

explosive (adjective)

likely to create difficulties or to have a dangerous or violent effect

fatal (adjective)

causing someone to die

ferocious (adjective)

violent and able to cause serious damage or injury

hairy (adjective)

informal frightening, or dangerous

hostile (adjective)

a hostile place or situation is difficult or dangerous to be in

hot (adjective)

difficult, or dangerous

ill (adjective)

bad, or harmful

inimical (adjective)

formal causing harm, or stopping the development of something

insidious (adjective)

something that is insidious is dangerous because it seems to be harmless or not important but in fact causes harm or damage

kamikaze (adjective)

a kamikaze action is dangerous and likely to kill or harm the person doing it

lethal (adjective)

very dangerous and able to kill you

lunatic (adjective)

extreme, or dangerous

malign (adjective)

literary causing harm

marauding (adjective)

going from place to place in order to find people to attack or things to steal or destroy

mortal (adjective)

likely to end with someone’s death

mortally (adverb)

in a way that is likely to cause death

nasty (adjective)

serious or dangerous

negative (adjective)

harmful, or bad

noxious (adjective)

harmful, or poisonous

overactive (adjective)

causing harm by being too active

parlous (adjective)

very formal full of dangers or difficulties

perilously (adverb)

mainly literary in a way that is dangerous or that can cause serious problems

pernicious (adjective)

formal very dangerous or harmful, especially to someone’s moral character

poisonous (adjective)

containing poison

poisonous (adjective)

causing a lot of damage or harm

precarious (adjective)

likely to change or become dangerous without warning

precarious (adjective)

not safe or likely to fall

prejudicial (adjective)

formal harmful to someone or something

serious (adjective)

bad or dangerous enough to make you worried

seriously (adverb)

in a way that is bad or dangerous enough to make you worried

sticky (adjective)

informal a sticky situation is difficult or dangerous

suicidal (adjective)

very dangerous, and likely to lead to serious problems or to death

suicide (noun)

used about an attack that will kill the person who makes it

suspect (adjective)

looking dangerous or illegal

terrible (adjective)

causing or involving serious harm or damage

threatening (adjective)

showing or saying that someone is likely to do something that will harm you

too hot to handle ()

too difficult or dangerous to get involved with

toxic (adjective)

poisonous and harmful to people, animals, or the environment

treacherous (adjective)

very dangerous, especially because the dangers are not obvious

undesirable (adjective)

bad, or harmful

unsound (adjective)

not safe

volatile (adjective)

a volatile situation can suddenly change or become more dangerous

wanton (adjective)

formal causing harm or damage for no reason