Soldier
From the Simple English Wikipedia, the free encyclopedia that anyone can change
A soldier is someone who fights in a war as a part of an army.
If people fight in irregular forces (forces not wearing a uniform, and not part of the official military of a nation), they are called partisans if they fight against another nation's army, or terrorists, if they fight civilians.
Partisans and terrorists are protected by the law to a lesser degree than soldiers.
Soldiers can be volunteers or conscripts (their nation calls upon them to fight). If they volunteer, but fight only because of the money, and not for their freedom or their nation, they are called mercenaries.