• synonyms

C, c

noun, plural C's or Cs, c's or cs.
  1. the third letter of the English alphabet, a consonant.
  2. any spoken sound represented by the letter C or c, as in cat, race, or circle.
  3. something having the shape of a C.
  4. a written or printed representation of the letter C or c.
  5. a device, as a printer's type, for reproducing the letter C or c.
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  1. Optics, Physics. the velocity of light in a vacuum: approximately 186,000 miles per second or 299,793 kilometers per second.
  2. Acoustics, Physics. the velocity of sound.
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  1. (with a year) about: c1775.
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Origin of c1

From the Latin word circā, circiter, circum


  1. calorie.
  2. Optics. candle; candles.
  3. Physics, Chemistry. curie; curies.
  4. cycle; cycles.
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  1. cocaine.
  2. Grammar. complement.
  3. consonant.
  4. coulomb.
  5. county (used with a number to designate a county road): C55.
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  1. the third in order or in a series.
  2. (sometimes lowercase) (in some grading systems) a grade or mark, as in school or college, indicating the quality of a student's work as fair or average.
  3. Music.
    1. the first tone, or keynote, in the scale of C major or the third tone in the relative minor scale, A minor.
    2. a string, key, or pipe tuned to this tone.
    3. a written or printed note representing this tone.
    4. (in the fixed system of solmization) the first tone of the scale of C major, called do.
    5. the tonality having C as the tonic note.
    6. a symbol indicating quadruple time and appearing after the clef sign on a musical staff.
  4. (sometimes lowercase) the Roman numeral for 100.
  5. Celsius.
  6. centigrade.
  7. Electricity.
    1. capacitance.
    2. a battery size for 1.5 volt dry cells: diameter, 1 inch (2.5 cm); length, 1.9 inches (4.8 cm).
  8. Chemistry. carbon.
  9. Physics.
    1. charge conjugation.
    2. charm1(def 9).
  10. Biochemistry.
    1. cysteine.
    2. cytosine.
  11. Also C-note. Slang. a hundred-dollar bill.
  12. a proportional shoe width size, narrower than D and wider than B.
  13. a proportional brassiere cup size, smaller than D and larger than B.
  14. the lowest quality rating for a corporate or municipal bond.
  15. Computers. a high-level programming language: very powerful and flexible, it is used in a wide variety of applications.
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  1. (in prescriptions) with.
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Origin of

From the Latin word cum


U.S. Military.
  1. (in designations of transport aircraft) cargo: C-54; C-124.
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  1. (with a year) about: c. 1775.
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Origin of c.1

From the Latin word circā, circiter, circum


  1. gallon.
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Origin of c.2

From the Latin word congius


  1. (in prescriptions) with.
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Origin of c.3

From the Latin word cum



  1. Calorie.
  2. Cape.
  3. Catholic.
  4. Celsius.
  5. Celtic.
  6. Centigrade.
  7. College.
  8. (in Costa Rica and El Salvador) colon; colons.
  9. Congress.
  10. Conservative.
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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Examples from the Web for c

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British Dictionary definitions for c



noun plural c's, C's or Cs
  1. the third letter and second consonant of the modern English alphabet
  2. a speech sound represented by this letter, in English usually either a voiceless alveolar fricative, as in cigar, or a voiceless velar stop, as in case
  3. the third in a series, esp the third highest grade in an examination
    1. something shaped like a C
    2. (in combination)a C-spring
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symbol for
  1. centi-
  2. cubic
  3. cycle
  4. maths constant
  5. specific heat capacity
  6. the speed of light and other types of electromagnetic radiation in a vacuum
  7. chess See algebraic notation
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symbol for
  1. music
    1. a note having a frequency of 261.63 hertz (middle C) or this value multiplied or divided by any power of 2; the first degree of a major scale containing no sharps or flats (C major)
    2. a key, string, or pipe producing this note
    3. the major or minor key having this note as its tonic
    4. a time signature denoting four crotchet beats to the barSee also alla breve (def. 2), common time
  2. chem carbon
  3. biochem cytosine
  4. capacitance
  5. heat capacity
  6. cold (water)
  7. physics compliance
  8. Celsius
  9. centigrade
  10. centuryC20
  11. coulomb
  12. (Roman numeral) 100See Roman numerals
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abbreviation for
  1. Cuba (international car registration)
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  1. a computer programming language combining the advantages of a high-level language with the ability to address the computer at a level comparable with that of an assembly language
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abbreviation for (of US military aircraft)
  1. cargo transportC-5
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abbreviation for
  1. carat
  2. cricket caught
  3. cent(s)
  4. century or centuries
  5. (used esp preceding a date) circac. 1800
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Word Origin

(for sense 5) Latin: about


abbreviation for
  1. (on maps as part of name) Cape
  2. Catholic
  3. Celtic
  4. Conservative
  5. Corps
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for c


third letter of the alphabet. Alphabetic writing came to Rome via the southern Etruscan "Caeretan" script, in which gamma was written as a crescent. Early Romans made little use of Greek kappa and used gamma for both the "g" and "k" sounds, the latter more frequently, so that the "k" sound came to be seen as the proper one for gamma. To restore a dedicated symbol for the "g" sound, a modified gamma was introduced c.250 B.C.E. as G. In classical Latin -c- has only the value "k," and thus it passed to Celtic and, via Irish monks, to Anglo-Saxon, where -k- was known but little used.

In Old French, many "k" sounds drifted to "ts" and by 13c., "s," but still were written with a -c-. Thus the 1066 invasion brought to the English language a more vigorous use of -k- and a flood of French and Latin words in which -c- represented "s" (e.g. cease, ceiling, circle). By 15c. native English words with -s- were being respelled with -c- for "s" (e.g. ice, mice, lice). In some words from Italian, meanwhile, the -c- has a "ch" sound (a sound evolution in Italian that parallels the Old French one).

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Online Etymology Dictionary, © 2010 Douglas Harper

c in Medicine


  1. blood capillary
  2. small calorie
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

c in Science


  1. The symbol for the speed of light in a vacuum.
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  1. The symbol for carbon.
  2. Abbreviation of capacitance, capacitor, capacity, Celsius, charge conjugation, coulomb, cytosine
  3. A programming language developed in 1972 and commonly used for writing professional software. With only a small number of built-in functions, it requires less memory than other languages, and because most if its functions are not specific to particular computers, it can be used on many different kinds of machines. The Unix operating system was written in C.
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  1. A naturally abundant, nonmetallic element that occurs in all organic compounds and can be found in all known forms of life. Diamonds and graphite are pure forms, and carbon is a major constituent of coal, petroleum, and natural gas. Carbon generally forms four covalent bonds with other atoms in larger molecules. Atomic number 6; atomic weight 12.011; sublimation point above 3,500°C; boiling point 4,827°C; specific gravity of amorphous carbon 1.8 to 2.1, of diamond 3.15 to 3.53, of graphite 1.9 to 2.3; valence 2, 3, 4. See Periodic Table.
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Related formscarbonaceous adjective
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.