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).

One who opposes another physically (in a fight, sport, game, or competition). / One who opposes another in words (in a dispute, argument or controversy).

(obsolete) Opposing; adverse; antagonistic. / (obsolete) Situated in front; opposite.

The practice of taking advantage of any situations or people to achieve an end, often with no regard for principles or consequences.

In an opportunistic manner.

In a manner suitable for some particular purpose. / In a manner convenient or advantageous at some particular time.

plural of opportunism

(obsolete) To oppose.

One who opposes, one who shows opposition.

plural of opportunist