decametre

A decametre is a unit of length in the metric system equal to ten metres. Its symbol is dam, formed from the prefix deka- meaning ten, attached to the metre. Therefore, 1 dam equals 10 metres, and conversely, 1 metre equals 0.1 decametre. In kilometre terms, 1 kilometre equals 100 decametres, and 1 decametre equals 0.01 kilometres.

The decametre is an SI-derived unit, but it is not commonly used in everyday measurement. It is occasionally encountered in technical contexts where lengths are too large for metres but too small for kilometres, such as certain surveying, forestry, or geographical applications, as well as in teaching to illustrate SI prefixes.

Etymology and naming: the term decametre combines the Greek deka, meaning ten, with metre. The symbol dam is the standard abbreviation used in scientific and engineering contexts.

See also: metre, kilometre, and SI units. The decametre demonstrates how the decimal prefixes of the metric system attach to base units to form slightly larger units, even when the resulting units see limited practical use.