decimation

Decimation is a term with multiple related meanings. Its root is the Latin decimus, meaning "tenth," and decimare, "to take a tenth." In classical Roman military practice, decimation referred to a punishment in which one man in every ten of a cohort or other unit was killed by lot, typically to punish collective cowardice, desertion, or mutiny. Historical accounts vary, and the exact application of the punishment is debated, but the term has persisted in modern usage as a severe reduction or destruction of a group.

Today, decimation is often used more loosely to describe any drastic decrease in number or extent, such as populations, economies, or organizations. In many contexts, the ordinary meaning is understood metaphorically, though some scholars caution that applying it to a percentage other than ten can be imprecise.

In science and engineering, decimation refers to downsampling a signal or dataset by a fixed integer factor. In digital signal processing, decimation reduces the sampling rate by a factor N, usually after applying a low-pass filter to prevent aliasing. In image processing, decimation can describe shrinking an image by selecting every nth pixel or through filtering, resampling, and interpolation methods.

The term shares its origin with decimate as a verb, but decimation as a noun describes the act or result of reducing by ten percent or more, depending on context. It remains common in both historical and technical discussions, often as a general description of loss or attrition rather than a precise measurement.