- a|gainstW1S1 [əˈgenst, əˈgeınst US əˈgenst] prep[Date: 1300-1400; Origin: againes 'against' (11-16 centuries), from again]1.)a) used to say that someone opposes or disagrees with something▪ Every council member voted against the proposal.▪ those who are campaigning against the new road▪ He advised me against travelling.▪ Mr Howard has declared that he is against all forms of racism.▪ the fight against terrorismb) used to say that an action is not wanted or approved of by someone▪ They got married against her parents' wishes (=although they knew her parents did not want them to) .▪ She has been kept in the house against her will (=she does not want to stay in the house) .▪ The use of certain drugs is against the law (=illegal) .▪ It's against my principles to borrow money (=I do not believe it is right) .c) used to say that something is not allowed by a law or rule▪ There ought to be a law against it.2.) used to say who someone is competing with or trying to defeat in a game, battle etc▪ Gambotti was injured in last Saturday's game against the Lions.▪ We'll be competing against some of the best companies in Europe.3.) used to say who is harmed, threatened, or given a disadvantage▪ violence against elderly people▪ crimes against humanity▪ discrimination against women▪ There had been death threats against prison staff.▪ Your lack of experience could count against you.▪ The regulations tend to work against smaller companies.4.) used to say that something touches, hits, or rubs a surface▪ the sound of the rain drumming against my window▪ The car skidded and we could hear the crunch of metal against metal.5.) next to and touching an upright surface, especially for support▪ There was a ladder propped up against the wall.▪ The younger policeman was leaning against the bureau with his arms folded.6.) in the opposite direction to the movement or flow of something≠ ↑with▪ sailing against the wind▪ She dived down and swam out strongly against the current.7.) seen with something else behind or as a background▪ He could see a line of figures silhouetted against the sky.▪ It is important to know what colours look good against your skin.8.) used to show that you are considering particular events in relation to other events that are happening at the same time▪ The reforms were introduced against a background of social unrest.9.) used to say what you are comparing something with▪ The pound has fallen 10% against the dollar.▪ She checked the contents of the box against the list.▪ The cost of the proposed research needs to be balanced against its benefits.10.)used to say who or what you are trying to protect someone or something from▪ insurance against accident and sickness▪ a cream to protect against sunburn▪ a vaccine which is effective against pneumonia11.) used to say who is said or shown to have done something wrong▪ He has always emphatically denied the allegations against him.▪ The evidence against you is overwhelming.12.) be/come up against sb/sthto have to deal with a difficult opponent or problem▪ You see, this is what we're up against - the suppliers just aren't reliable.13.) have sth against sb/sthto dislike or disapprove of someone or something▪ I don't have anything against babies. I just don't feel very comfortable with them.
Dictionary of contemporary English. 2013.