First coined by Omega, a member of the retro hacking group Cult of the Dead Cow, in the mid-90s, 'hacktivism' was defined as the use of computer hacking to express political or sociological beliefs. The meaning of the term was loose and could span passive actions, such as just expressing an idea, to malicious attacks targeting ideological opponents.
According to dictionary.com a hacktivist is a person who gains unauthorized access to computer files or networks in order to further social or political ends. Hacktivism is the act of misusing a computer system or network for a socially or politically motivated reason. Individuals who perform hacktivism are known as hacktivists.