[Latin decimus, tenth.]
The decimal system of counting is one of numbers and arithmetic based on the number ten; to decimate originally meant to kill one in every ten of a group, but in current usage it refers to any large proportion; a decile is each of ten equal groups into which a population can be divided according to the distribution of values of a variable. For decillion see the entry Number words. A decibel (one tenth of a bel, a unit too large for practical convenience) is used to measure the intensity of a sound or an electrical signal by comparing it with a given level on a logarithmic scale; other examples in units of measurement include decilitre and decimetre (US deciliter and decimeter). It is one of the standard SI (Système International) multiples (see the entry Words for multiples).