Deci-

File:France, decim 1798-1799, the First Republic.jpg

French 1 decime coin, equal to Template:Sfrac of a franc. First Republic.

Deci (symbol d) is a decimal unit prefix in the metric system denoting a factor of one tenth. Proposed in 1793,<ref name="CTPM_1793">Template:Cite book</ref> and adopted in 1795, the prefix comes from the Latin Template:Lang, meaning "tenth". Since 1960, the prefix is part of the International System of Units (SI).<ref>Template:Cite book</ref><ref>Template:Cite web</ref>

A frequent use of the prefix is in the unit deciliter (dl), common in food recipes; many European homes have a deciliter measure for flour, water, etc. A common measure in engineering is the unit decibel for measuring ratios of power and root-power quantities, such as sound level and electrical amplification.

Example

• The diameter of a compact disc is about 12 centimetres or 1.2 decimetres.<ref>Template:Cite web</ref>