Decimation originally referred to a form of military punishment in ancient Rome, where one in every ten soldiers in a mutinous group was executed. The term derives from the Latin "decimatio," meaning "removal of a tenth." In modern usage, decimation has come to describe any significant destruction or reduction of a group or population, often in a more general sense. It can also apply to contexts like ecology or data analysis, where a large portion of a dataset or species is removed or diminished.