strong disagreement

There is a lot of opposition to the proposed changes. 对所提出的变革有很多反对意见。

The unions are in opposition to the government over the issue of increasing the minimum wage. 工会在提高最低工资一事上强烈反对政府。

the team or person being played against in a sports competition

The opposition has/have some good players so it should be a tough match. 对方有一些不错的选手，所以要赢得这场比赛会很艰难。

in some political systems, the elected politicians who belong to the largest party that does not form the government

the Leader of the Opposition 反对党领袖

The Opposition has/have condemned the government's proposed tax increases. 反对党谴责了政府提高税率的提议。