This is the 14146th most frequent Russian word.
оппозиционер
An oppositionist; a person who opposes or is against the ruling authority or government.
Here, 'оппозиционер' is used to describe a collective group of people opposing authority.
Группа оппозиционеров организовала митинг в центре города.
A group of oppositionists organized a rally in the city center.
Here, 'оппозиционер' is used as a noun describing a person who opposes the current government.
Оппозиционер выступил с критикой действующего правительства.
The oppositionist spoke out with criticism of the current government.
In this sentence, 'оппозиционер' refers to an individual embracing opposition ideologies while supporting community interests.