mu·ja·hid 
(m-jähĭd′)
(m-jähĭd′)n. pl. mu·ja·hi·deen or mu·ja·hi·din (m-jä′hĕ-dēn)
1. One engaged in a jihad, especially as a guerrilla warrior.
2. One of the Muslim guerrilla warriors that resisted the Soviet invasion of Afghanistan in the 1980s with the support of the United States and Pakistan.
[Ultimately (partly via Persian) from Arabic mujāhid, one who fights in a jihad, active participle of jāhada, to fight; see ghd in the Appendix of Semitic roots.]