war is any large scale, violent conflict. The conduct of
war extends along a continuum, from the almost universal
tribal warfare that began well before recorded human history, to
wars between
city states, nations, or empires. By extension, the word is now used for any struggle, as in the
war on drugs or the
war on terror. It was once thought humans were the only creatures who fought
wars, but closer observation of animal life has discovered
wars between ant colonies and chimpanzee tribes.
http://en.wikipedia.org/wiki/war 
