A side, party (e.g. a team or armed force) seen as adversary, enemy etc. opposite one (or more) other(s), as in a battle or team sports competition.

The complete opposite, opposite in every way.

plural of opposite side

(idiomatic) Holding starkly opposite views on an issue.

(politics) Negative information retrieved about a candidate's opponent in an election for use in campaigning.

A recognized political party or group of parties in multiparty political systems that is present in Parliament or some other legislative body and does not control the floor (usually due to being in the minority).

(fencing) The deflection of the incoming attack without ever losing contact with the blade from the initial engagement.

plural of Leader of the Opposition

(politics, UK) In a house of legislature following the model of the Westminster system (such as the UK House of Commons), the parliamentary leader of the largest political party not forming the government.

(politics, sometimes attributive) The force acting against the opposition.