Battle
A battle is an instance of armed combat in which military opponents attempt to defeat each other. Battles are usually considered to be one instance of conflict, even though they may be protracted (long and drawn out) and take place over hours or days. Successive military battles are often part of a larger war.
When several battles with the same goal are fought over time, they are often termed a campaign, which indicates both their focus and the fact that the battles took place over a lenghthy period.
Military conflict
Other uses of the term
By extension, any protracted contest, argument, disptute or fight that can be likened in intensity to a military battle can be referred to as a 'battle'. In this sense, the conflict can be friendly or unfrinendly, and can be verbal, physical or mental.