What are the meanings of Jihad in the Quran?
Jihad جهاد is derived from Jahd جهد , which means to attempt to use all means of power in order to accomplish something. In the verses that were revealed of the Meccan period Jihad had the following meanings:
♦ Strive, struggle (Al-Ankabut  69).
♦ To do something with ones full strength ( Al-‘An’am  109).
♦ Force (assigning other gods, inflicted on the children from the parents (Al-‘An’am  8, Luqman  15).
♦ Convey the Quran [The greatest Jihad] (Al-Furqan  52).
In the verses of the Medina phase one more meaning was added to the other 4 meanings: Defensive Warfare against an aggression. Therefore Jihad also has the meaning of war, but that is only an indirect meaning (e.g. an-Nisa  95). The words used for war in the Quran are Harb حرب and Qital قتال . Out of this arises that Jihad doesn’t exclusively mean battle with weapons against an aggressor, but all endeavours with regard to the faith and including the Religion.
(Thanks a lot to Prof.Dr. Mehmet Okuyan and Prof.Dr. Murat Sulun)