Noun

(en noun)

One who protests, either singly or in a public display of group feeling.

* {{quote-magazine, date=2013-06-07, author=(Gary Younge)

, volume=188, issue=26, page=18, magazine=(The Guardian Weekly) , title= Hypocrisy lies at heart of Manning prosecution , passage=The dispatches […] also exposed the blatant discrepancy between the west's professed values and actual foreign policies. Having lectured the Arab world about democracy for years, its collusion in suppressing freedom was undeniable as protesters were met by weaponry and tear gas made in the west, employed by a military trained by westerners.}}

(legal) One who protests a bill of exchange, or note.

Noun

(en noun)

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

*{{quote-magazine, date=2013-08-10, volume=408, issue=8848, magazine=(The Economist)

, title= Can China clean up fast enough? , passage=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.}}

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