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The following statistics are based on the British National Corpus, so they are representative for the British English.

Distribution of usage frequency for the most common synonyms of the noun A:


A is sometimes a misspelling of all, an, and, any, as, at, have, our, the or us.

The word a is considered to be an easy one, according to the Dale-Chall word list, which includes 3000 words that all fourth-grade American students should know and understand.

Definition of the noun a

What does a mean as a name of something?

noun - plural: As

  1. a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
  2. any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
  3. one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)
  4. (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
    • domain: biochemistry
    • lexical domain: Substances - nouns denoting substances
    • synonym of A: adenine
    • more generic word: purine = any of several bases that are derivatives of purine
    • substance of: deoxyribonucleic acid / desoxyribonucleic acid / DNA = a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix; ribonucleic acid / RNA = a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes
  5. the basic unit of electric current adopted under the Systeme International d'Unites
    • example: a typical household circuit carries 15 to 50 amps
    • lexical domain: Quantities - nouns denoting quantities and units of measure
    • synonyms of A: amp / ampere
    • more generic term: current unit = a measure of the amount of electric charge flowing past a circuit point at a specific time
    • part of: abamp / abampere = a unit of current equal to 10 amperes
    • part: milliampere / mA = one thousandth of an ampere
  6. the 1st letter of the Roman alphabet
  7. the blood group whose red cells carry the A antigen

Alternative definition of the noun a


  1. Latn-def, en, name, A, a
  2. [context: often capitalized] The best grade; superiority.

Other definitions of a

What does a also mean?


  1. [context: on bills, etc.] accepted
  2. ante; before
  3. [linguistics] active
  4. See adjective.
  5. An are, a unit of area of which 100 comprise a hectare.


  1. One; any indefinite example of.
  2. One certain or particular.
  3. The same; one.
  4. Any, every.


  1. A meaningless syllable; ah.


  1. Latn-def, en, letter, 1, a


  1. Latn-def, en, ordinal, 1, a


  1. [archaic] In, on, at, by.
  2. [archaic] In the process of; in the act of; into; to. [Used with verbal substantives in -ing which begin with a consonant.]
  3. [archaic] Of.
  4. To, each, per.


  1. He; she; it; they.


  1. Latn-def, en, letter, 1, a


  1. Latn-def, en, ordinal, 1, a


  1. The highest rank on any of various scales that assign letters.
    • synonym: Å
  2. [context: education] The highest letter grade assigned (disregarding plusses and minuses).
  3. [music] A tone three fifths above C in the cycle of fifths; the sixth tone of the C major scale; the reference tone that occurs at exactly 440 Hz.
  4. [medicine] A blood type that has a specific antigen that aggravates the immune response in people with type B antigen in their blood. They may receive blood from type A or type O, but cannot receive blood from AB or B.
  5. [context: vehicle-distinguishing signs] Austria

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