| This definition is now outdated. Islamism now refers not to the practice of Islam, but specifically to Muslim fundamentalism, of the type pioneered by the Muslim Brotherhood (which coined the term) in the 1940s. It is a more correct term than Muslim fundamentalism, because fundamentalism originally refers to a type of evangelical Protestantism, and slapping it on a bunch of Muslim fanatics is incorrect.
Islamism is today a movement to impose Islamic rule, according to the Shari'a, on the entire Islamic world, and to convert the non-Islamic world to Islamic. It is characterized by extreme violence, virulent anti-Semitism, and rejection of Western Civilization and modernity. Prominent Islamist organization include al-Qaeda, the Muslim Brotherhood, Hezbollah, and the governments of Iran and Saudi Arabia.
Jaez, you are incorrect. First off, 'Islamism', as currently used, was coined by the Muslim Brotherhood. Second, compulsion in matters of religion appears to be standard operating procedure for countries with Islamic governments, in ways ranging from the death penalty for apostasy to restrictions on the activities of other religious groups. You have also ignored the signifigance of conversion by the sword in Muslim history, especially in the breakout from Arabia.
I'm entirely willing to entertain the idea that the Islamicists (or fundamentalists or militants, or whatever you care to call them) are not practicing true Islam. In fact, I rather hope they are not; however, most of the larger mainstream Muslim groups, such as the CAIR in the US, have failed to distance themselves sufficiently from the militants and other assorted god-botherers.
In some ways, I can understand this position -- the Muslim Brotherhood in particular started as a group pressing for human rights and greater freedoms in Egypt; they did not turn towards violence and extremism until Nasser brutally suppressed them. However, their history since that time has been increasingly violent.
The goals of al-Qaeda are spelled out in bin Laden's declaration of war on the United States, and his other writings, helpfully archived (in English) by the Muslim Students Association. Sey Hirsh has published a series of articles in the New Yorker and elsewhere detailing the corruption of the Saudi regime and its involvement in and funding of the Islamist movement. Iran's support for Hezbollah and other Islamist organizations is well known, as is their own form of theocratic government. Comfortingly, the mullahs are alienating the Iranian people by (mis)ruling them.
As for anti-Semitism, the word means hatred of the Jews, and all the linguistic fiddling in the world will not change that. Destruction of the state of Israel, or its conversion into a Muslim state is a dangerous fantasy that stands in the way of a real solution in the Middle East. Peaceful co-existence is the only solution.
Standing in the way of this is the poisonously anti-Semitic propanda popular in the Arab world, including (but certainly not limited to) revival of the blood libel and celebration of the cult of the suicide bomber. | 
