against
preposition For the special uses of against in phrasal verbs, look at the entries for the verbs. For example count against somebody is in the phrasal verb section at count.Idioms-
opposing or disagreeing with somebody/something 反对；与…相反；逆；违反 the fight against terrorism 反对恐怖主义的斗争 We're playing against the league champions next week. 下周我们要和联赛冠军队比赛。 We were rowing against the current. 我们划船逆流而上。 That's against the law. 那是违法的。 She was forced to marry against her will. 她被迫违背自己的心愿嫁了人。 Are you for or against the death penalty? 你赞成还是反对死刑？ She is against seeing (= does not want to see) him. 她不想见他。 I'd advise you against doing that. 我劝你别做那事。
not to the advantage or favour of somebody/something 对…不利 close to, touching or hitting somebody/something 紧靠；倚；碰；撞 in order to prevent something from happening or to reduce the damage caused by something 以防 with something in the background, as a contrast 以…为背景；衬托 used when you are comparing two things 和…相比
Word OriginMiddle English: from again + -s (adverbial genitive) + -t probably by association with superlatives (as in amongst).
Idioms
as against something
in contrast with something 与…相对照；和…相比较 They got 27 per cent of the vote as against 32 per cent at the last election. 他们获得了27%的选票，而上次选举时为32%。
the cards/odds are stacked against you
you are unlikely to succeed because the conditions are not good for you 形势对你不利