Yours, Etc.: Origins and Uses of 8 Sign-Offs
in the metric system, word-forming element denoting weights of one-tenth of the standard unit of measure, 1801, from French deci-, taken arbitrarily from Latin decimus "tenth," from decem "ten" (see ten).
One tenth (10-1): decibel.
A prefix that means "one tenth," as in deciliter, one tenth of a liter.