activist

noun

1. One who is politically active in the role of a citizen; especially, one who campaigns for change.

   “It has jailed environmental activists and is planning to limit the power of judicial oversight by handing a state-approved body a monopoly over bringing environmental lawsuits.”

   “The six activists will now face a retrial at Highbury Magistrates' Court, in front of a new judge.”

2. One who is conspicuously active in carrying out any occupational or professional functions.

adj

1. Behaving as an activist.

   “Even in the area of free speech, Justice Harlan sometimes emerged as more activist than his brother”

   “Now GM has what may well be the most activist board ever.”

   “Gov. Chris Christie has long complained that New Jersey's Supreme Court is too liberal and too activist”