to think something is wrong► be against/be opposed to to think that something is wrong and that it should not be allowed: · Lundgren is against abortion.· Most people are opposed to the privatization of the city's public transportation system.be strongly against: · There are two or three groups that are strongly against construction of the dam.be dead set against (=be very much against something): · She wants to marry him, but her parents are dead set against it.be strongly/totally/opposed to: · Senator Thompson remains totally opposed to any form of gun control.
► oppose to think that a plan, idea etc is wrong, and to try to prevent it from happening or succeeding: · Conservative MPs say they will oppose the new bill.strongly/vigorously oppose: · The Church strongly opposes same-sex marriage.
► not agree with something especially spoken to be against something, for example because it is new or different and you do not like things to change: · My grandmother doesn't agree with divorce.· There are many people in the US who do not agree with capital punishment.
► not believe in something to not support something, because you think something is wrong or immoral: · Fiona doesn't believe in having sex before marriage.· I don't believe in hitting children for any reason.
► anti-: anti-war/-smoking/-American etc against war, smoking, America etc: · Anti-war demonstrators gathered in the city's main square.· The anti-smoking laws seem ridiculous to me.· Anti-American sentiment remains high in the region.
► hostile someone who is hostile to a plan or idea opposes it very strongly, and expresses this in an angry way: · A hostile audience refused to listen to Senator Drummond's reply.hostile to/towards: · Local people are hostile towards the plan, which would involve a significant tax increase.openly hostile (=showing very clearly that you are hostile): · Lydon was openly hostile to any kind of criticism of the project.
► antagonistic behaving in a way that shows that you strongly disapprove of someone or something: · A lot of people refuse to work with Paula. Her manner is just too antagonistic.antagonistic to/towards: · The right-wing press has always been deeply antagonistic towards the Labour party.
1opposed to OPP pro-: 
antinuclear (=opposing the use of nuclear weapons and power)