struggle / striving (in God's cause)
Masculine verbal noun (maṣdar) of جَاهَدَ (Form III). Related: جُهْدٌ (effort), مُجَاهِدٌ (one who strives), اجْتِهَادٌ (scholarly reasoning). The verb means 'to exert effort.'
Jihād primarily means 'inner spiritual struggle' against one's own shortcomings (the 'greater jihād'). The Prophet ﷺ called the struggle against the ego the greatest jihād.