The following is a blog entry from http://justsaynotoreligion.com/ and attempts to provide a definition of jihad. The date is unknown, but it may have been written in mid 2007.
Jihad is to strive or struggle in the way of God, and is sometimes referred to as the sixth pillar of Islam, although it has no official status. Jihad has a wider meaning in Islamic literature. It can be striving to lead a good Muslim life, praying and fasting regularly, being an attentive spouse and parent or working hard to spread the message of Islam. Jihad is also used in the meaning of struggle for or defence of Islam, the holy war. Despite the fact that Jihad is not supposed to include aggressive warfare, this has occurred, as exemplified by early extremists like Kharijites and contemporary groups like Egypt‘s Jihad Organization (which assassinated Anwar Al Sadat) as well as Jihad organizations in Lebanon, the Gulf states, and Indonesia.
In Muhammad’s time, after Itmam al-hujjah (completion of the proof, a doctrine in Islam related to prophets), polytheists of Arabia were asked for submission to Islam as a condition for exoneration and the others for jizya and submission to the political authority of the Muslims for exemption from death punishment and for military protection as the dhimmis of the Muslims. Islamic scholars have different opinions on Jihad, however, there is a consensus that armed struggle against persecution and oppression will always continue.