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• deci-
  deci-

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

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

deci-

American  

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

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deci- British  

prefix

1.  d.  denoting one tenth; 10 ^–1

   decimetre

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deci– Scientific  

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

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Usage

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).

Etymology

Origin of deci-

< French déci- < Latin decimus tenth