C

UK:**UK and possibly other pronunciationsUK and possibly other pronunciations'C', 'c': /ˈsiː/US:USA pronunciation: IPA and respellingUSA pronunciation: IPA'C', 'c': /si/ ,USA pronunciation: respelling'C', 'c': (sē)


Collins Concise English Dictionary © HarperCollins Publishers::
C symbol for
    • 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)
    • the major or minor key having this note as its tonic
    • a time signature denoting four crotchet beats to the bar See also alla breve, common time
  2. carbon
  3. cytosine
  4. capacitance
  5. heat capacity
  6. cold (water)
  7. compliance
  8. Celsius
  9. centigrade
  10. century: C21
  11. coulomb
  12. (Roman numeral) 100 See Roman numerals
 abbreviation for
  1. Cuba (international car registration)
 n
  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
WordReference Random House Learner's Dictionary of American English © 2026
C, c /si/USA pronunciation   n. [countable], pl. Cs or C's, cs or c's. 
  1. Linguisticsthe third letter of the English alphabet, a consonant.

C,  Symbol.
  1. Education[sometimes: c] (in some grading systems) a grade or mark indicating fair or average quality.
  2. Music and Dance
    • the tonic note of the C major scale.
    • a written or printed note representing this tone.
  3. [sometimes: c] the Roman numeral for 100.
  4. PhysicsCelsius:The temperature is 10°C (said as "10 degrees Celsius'').
  5. Physicscentigrade.
  6. Chemistrycarbon.
  7. Also, C-note. Slang. a hundred-dollar bill.

c,  an abbreviation of: circa
  1. (used with a year):c1775.

c, [Symbol.]
  1. Optics, Physicsthe velocity of light in a vacuum: approximately 186,000 miles per second or 299,793 kilometers per second.
  2. Physicsthe velocity of sound.

C.,  an abbreviation of:
  1. ThermodynamicsCalorie.
  2. EducationCollege.
  3. Conservative.

c.,  an abbreviation of:
  1. Thermodynamicscalorie.
  2. Jewelrycarat.
  3. Physicscentigrade.
  4. Weights and Measurescentimeter.
  5. chapter.
  6. circa (used with a year):c. 1775.
  7. copyright.
  8. Weights and Measurescubic.

WordReference Random House Learner's Dictionary of American English © 2026
ˈRo•man ˈnu•mer•al,  n. [countable]
  1. any of the numerals in the ancient Roman system of notation, still used occasionally. The basic symbols are I (=1), V (=5), X (=10), L (=50), C (=100), D (=500), and M (=1000).

WordReference Random House Unabridged Dictionary of American English © 2026
C, c  (sē),USA pronunciation n., pl. 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 aC.
  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.

C, 
    1. Drugscocaine.
    2. Education, Grammar[Gram.]complement.
    3. Music and Danceconsonant.
    4. Physicscoulomb.
    5. county (used with a number to designate a county road):C55.

C,  Symbol.
  1. the third in order or in a series.
  2. (sometimes l.c.) (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.]
    • Phoneticsthe first tone, or keynote, in the scale of C major or the third tone in the relative minor scale, A minor.
    • Music and Dancea string, key, or pipe tuned to this tone.
    • Phoneticsa written or printed note representing this tone.
    • (in the fixed system of solmization) the first tone of the scale of C major, called do.
    • the tonality having C as the tonic note.
    • a symbol indicating quadruple time and appearing after the clef sign on a musical staff.
  4. (sometimes l.c.) the Roman numeral for 100.
  5. Celsius.
  6. centigrade.
  7. [Elect.]
    • capacitance.
    • a battery size for 1.5 volt dry cells: diameter, 1 in. (2.5 cm);
      length, 1.9 in. (4.8 cm).
  8. Chemistrycarbon.
  9. [Physics.]
    • charge conjugation.
    • charm1 (def. 9).
  10. [Biochem.]
    • cysteine.
    • cytosine.
  11. Also, C-note. [Slang.]a hundred-dollar bill.
  12. Clothinga proportional shoe width size, narrower than D and wider than B.
  13. Clothinga proportional brassiere cup size, smaller than D and larger than B.
  14. Stock Exchange, Businessthe lowest quality rating for a corporate or municipal bond.
  15. Computinga high-level programming language: very powerful and flexible, it is used in a wide variety of applications.

c, 
    1. Drugscalorie.
    2. [Optics.]candle;
      candles.
    3. (with a year) about:c1775.
      • Latin circā, circiter, circum
    4. [Physics, Chem.]curie;
      curies.
    5. cycle;
      cycles.

c,  Symbol.
  1. [Optics, Physics.]the velocity of light in a vacuum: approximately 186,000 miles per second or 299,793 kilometers per second.
  2. Physics[Acoustics, Physics.]the velocity of sound.

c̄, 
  1. (in prescriptions) with.
  • Latin cum

C., 
    1. Calorie.
    2. Place NamesCape.
    3. ReligionCatholic.
    4. PhysicsCelsius.
    5. Celtic.
    6. PhysicsCentigrade.
    7. EducationCollege.
    8. Currency(in Costa Rica and El Salvador) colon;
      colons.
    9. GovernmentCongress.
    10. GovernmentConservative.

C-, [U.S. Mil.]
  1. Military(in designations of transport aircraft) cargo:C-54; C-124.

c., 
    1. calorie.
    2. Opticscandle;
      candles.
    3. Jewelrycarat.
    4. Chemistrycarbon.
    5. carton.
    6. case.
    7. [Baseball.]catcher.
    8. Electricitycathode.
    9. Currencycent;
      cents.
    10. Currencycentavo.
    11. [Football.]center.
    12. Physicscentigrade.
    13. Currencycentime.
    14. Weights and Measurescentimeter.
    15. century.
    16. chairman;
      chairperson.
    17. chapter.
    18. chief.
    19. child.
    20. church.
    21. (with a year) about:c. 1775.
      • Latin circā, circiter, circum
    22. Meteorologycirrus.
    23. city.
    24. cloudy.
    25. Linguisticscognate.
    26. color.
    27. Weights and Measuresgallon.
      • Latin circā, circiter, circum
    28. Chemistrycopper.
    29. copyright.
    30. corps.
    31. Weights and Measurescubic.
    32. (in prescriptions) with.
      • Latin circā, circiter, circum
    33. cycle;
      cycles.

C++, n. 
  1. Computinga high-level programming language, a descendant of C, with the ability to manipulate object-oriented features.

WordReference Random House Unabridged Dictionary of American English © 2026
Ro′man nu′merals, 
  1. the numerals in the ancient Roman system of notation, still used for certain limited purposes, as in some pagination, dates on buildings, etc. The common basic symbols are I (=1), V (=5), X (=10), L (=50), C (=100), D (=500), and M (=1000). The Roman numerals for one to nine are: I, II, III, IV, V, VI, VII, VIII, IX. A bar over a letter multiplies it by 1000;
    thus, X̄ equals 10,000. Integers are written according to these two rules: If a letter is immediately followed by one of equal or lesser value, the two values are added;
    thus, XX equals 20, XV equals 15, VI equals 6. If a letter is immediately followed by one of greater value, the first is subtracted from the second;
    thus, IV equals 4, XL equals 40, CM equals 900. Examples: XLVII(=47), CXVI(=116), MCXX(=1120), MCMXIV(=1914). Roman numerals may be written in lowercase letters, though they appear more commonly in capitals.
  • 1725–35

Collins Concise English Dictionary © HarperCollins Publishers::
c, C /siː/ n ( pl c's, C's, 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
  4. something shaped like a C
c symbol for
  1. centi-
  2. cubic
  3. cycle
  4. constant
  5. specific heat capacity
  6. the speed of light and other types of electromagnetic radiation in a vacuum
Collins Concise English Dictionary © HarperCollins Publishers::
C. abbreviation for
  1. (on maps as part of name) Cape
  2. Catholic
  3. Celtic
  4. Conservative
  5. Corps
Collins Concise English Dictionary © HarperCollins Publishers::
c. abbreviation for
  1. carat
  2. caught
  3. cent(s)
  4. century or centuries
  5. (used esp preceding a date) circa: c. 1800
Etymology: (for sense 5) Latin: about
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'C' also found in these entries (note: many are not synonyms or translations):
A - absolute zero - a/c - ACE inhibitor - acetanilide - acetylene - acridine - acriflavine - actinium - ad- - adenine - adenosine - adrenaline - Agrippina - Albert I - alcohol - Aldis lamp - aldrin - Alexander I - alginic acid - alizarin - alkene - alkyl - alto clef - aluminium - americium - amphetamine - amygdalin - amyl - amyl alcohol - androsterone - aniline - anthracene - antimony - antimony potassium tartrate - antioxidant - arabinose - argon - arsenic - ascorbic acid - asdic - aspartame - astatine - atmosphere - ATP - atrazine - atropine - augmented - B - balm of Gilead
Collocations: the letter C, got a C on the [test, exam], got a C on her report card, more...

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