Anarchism is a philosophy advocating the abolition of all forms of hierarchical authority, including capitalism and the state. Anarchists advocate the organization of society by voluntary non-hierarchical associations instead of hierarchical organizations such as corporations and the state. A constructive definition could be: voluntary cooperation for the good, with the right to secession. Anti-anarchist propaganda has succeeded in equating anarchism with chaos, violence and bomb-throwing in the public mind but this is a misrepresentation of anarchism - an example of a highly successful smear campaign based on libel and slander.
Some piggyback on these smears and attempt to discredit other ideas and movements by describing them as anarchist. It is sometimes used as a simple smear term, as part of libel and slander efforts against groups that have other goals.