deci-

1. a combining form meaning “tenth,” used in words denoting units of the metric system ( deciliter ); on this model, extended to other systems ( decibel ).

deci-

prefix

1. denoting one tenth; 10 ^–1 d

   decimetre

deci–

1. A prefix that means “one tenth,” as in deciliter, one tenth of a liter.

Word History and Origins

Origin of deci-¹

< French déci- < Latin decimus tenth

Word History and Origins

Origin of deci-¹

from French déci-, from Latin decimus tenth

Example Sentences

“To the $hock of nobody, Arkan$a$ racing official$ have made a que$tionable deci$ion to not $u$pend Bob Baffert over $everal drug infraction$. Immediate rea$on$ are not available.”

From Seattle Times

Ben Deci, a spokesman for the state Department of Consumer Affairs, said there’s no record of any enforcement actions taken against Atinger, which can mean his nose is clean or that no one ever filed an official complaint against him.

From Los Angeles Times

“If a consumer thinks they’ve been the victim of fraudulent pricing, or illegal collection practices, we urge them to file a complaint,” Deci said.

From Los Angeles Times

For the rest of us, follow Deci’s advice.

From Los Angeles Times

“Consumers should get a quote beforehand,” Deci said.

From Los Angeles Times

Words That Use Deci-

What does deci- mean?

Deci- is a combining form used like a prefix meaning “tenth.” It is most often used to denote units of the metric system.

Deci- comes from the Latin decimus, meaning “tenth.” The word decimate, meaning “to destroy a great number or proportion of” comes from this same Latin root. Find out how at our entry for decimate.

A similar word from Greek, déka, meaning “ten,” gives us the combining forms dec-, deca-, and deci-. Want to know more? Check out our Words That Use articles for all three forms.

Despite the similarity between the two forms, it’s important not to confuse deci-, which means “tenth,” with deca-, meaning “ten.” A decigram is one-tenth of a gram (0.1 g), but a decagram is ten grams (10 g).

Examples of deci-

One example of a technical term you may have encountered that features the combining form deci- is decimeter, “a unit of length equal to 1/10 of a meter.” Decimeter comes from the French décimètre, which uses the equivalent of the combining form deci-.

The first part of the word, deci-, means “tenth,” as we have seen. The combining form -meter has a variety of meanings, but in this case it refers to the metric unit “meter.” Decimeter literally means “a tenth of a meter.”

What are some words that use the combining form deci-?

• decibar
• decibel
• decillion (using the equivalent form of deci- in Latin)
• deciliter (using the equivalent form of deci- in French)
• decimal (using the equivalent form of deci- in Latin)

What are some other forms that deci- may be commonly confused with?

• dactylo-
• de-
• dextro-
• di-
• dodeca-

Not every word that begins with the exact letters dec- or deci-, such as decide and decision, is necessarily using the combining forming deci- to denote “tenth.” Learn where these words come from at our entries for decide and decision.

Break it down!

A liter is a unit used for measuring liquids. With this in mind, what is a deciliter?