noun, plural B’s or Bs, b’s or bs.

  1. the second letter of the English alphabet, a consonant.
  2. any spoken sound represented by the letter B or b, as in bid, bauble, or daubed.
  3. something having the shape of a B.
  4. a written or printed representation of the letter B or b.
  5. a device, as a printer’s type, for reproducing the letter B or b.

  1. Physics.
    1. bar; bars.
    2. barn; barns.
  2. black.

  1. Chess. bishop.
  2. black.
  3. Photography. bulb(def 8).


  1. the second 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 good or better than average.
  3. (sometimes lowercase) (in some school systems) a symbol designating the second semester of a school year.
  4. Physiology. a major blood group usually enabling a person whose blood is of this type to donate blood to persons of type B or AB and to receive blood from persons of type O or B.Compare ABO system.
  5. Music.
    1. the seventh tone in the scale of C major or the second 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 seventh tone of the scale of C major, called ti.
    5. the tonality having B as the tonic note.
  6. (sometimes lowercase) the medieval Roman numeral for 300.
  7. Chemistry. boron.
  8. a proportional shoe width size, narrower than C and wider than A.
  9. a proportional brassiere cup size, smaller than C and larger than A.
  10. Physics. magnetic induction.
  11. Electricity. susceptance.
  12. a designation for a motion picture made on a low budget and meant as the secondary part of a double feature.
  13. a quality rating for a corporate or municipal bond, lower than BB and higher than CCC.

U.S. Military.

  1. (in designations of aircraft) bomber: B-29.

  1. bachelor.
  2. bale.
  3. Baseball. base; baseman.
  4. bass.
  5. basso.
  6. bay.
  7. billion.
  8. blend of; blended.
  9. book.
  10. born.
  11. breadth.
  12. brother.
  13. brotherhood.

  1. bachelor.
  2. bacillus.
  3. Baseball. base; baseman.
  4. bass.
  5. basso.
  6. bay.
  7. Bible.
  8. bolivar.
  9. boliviano.
  10. book.
  11. born.
  12. breadth.
  13. British.
  14. brother.
  15. brotherhood.


  1. the second letter of the Greek alphabet (β, B).
  2. the consonant sound represented by this letter.
  3. (initial capital letter) Astronomy. a star that is usually the second brightest of a constellation: The second brightest star in Taurus is Beta Tauri.
  4. Chemistry.
    1. one of the possible positions of an atom or group in a compound.
    2. one of two or more isomeric compounds.
  5. the second of any series, as in chemistry or physics.
  6. Also called beta coefficient, beta line. Stock Exchange. an arbitrary measure of the volatility of a given stock using an index of the volatility of the market as a whole: A beta of 1.1 indicates a stock that is 10 percent more volatile than the market.
  7. (initial capital letter) Trademark. a brand of tape format for VCR tape, incompatible with other formats.Compare VHS.
  8. Chiefly British. a grade showing that a student is in the middle or second of three scholastic sections in a class.Compare alpha(def 7), gamma(def 9).

symbol for

  1. chess See algebraic notation

noun plural b’s, B’s or Bs

  1. the second letter and first consonant of the modern English alphabet
  2. a speech sound represented by this letter, usually a voiced bilabial stop, as in bell
  3. Also: beta the second in a series, esp the second highest grade in an examination

symbol for

  1. music
    1. a note having a frequency of 493.88 hertz (B above middle C) or this value multiplied or divided by any power of 2; the seventh note of the scale of C major
    2. a key, string, or pipe producing this note
    3. the major or minor key having this note as its tonic
  2. the supporting or less important of two thingsthe B side of a record
  3. a human blood type of the ABO group, containing the B antigen
  4. (in Britain) a secondary road
  5. the number 11 in hexadecimal notation
  6. chem boron
  7. magnetic flux density
  8. chess bishop
  9. (on Brit pencils, signifying degree of softness of lead) blackB; 2B; 3B Compare H (def. 5)
  10. Also: b physics bel
  11. physics baryon number
  12. balboa
  13. belga
  14. bolivar
  15. photog B-setting
    1. a person whose job is in middle management, or who holds an intermediate administrative or professional position
    2. (as modifier)a B worker See also occupation groupings

abbreviation for

  1. Belgium (international car registration)

abbreviation for (of US military aircraft)

  1. bomberB-52

abbreviation for

  1. born
  2. cricket bowled

abbreviation for

  1. (on maps, etc) bay
  2. British


  1. the second letter in the Greek alphabet (Β, β), a consonant, transliterated as b
  2. the second highest grade or mark, as in an examination
  3. (modifier)
    1. involving or relating to electronsbeta emitter
    2. relating to one of two or more allotropes or crystal structures of a solidbeta iron
    3. relating to one of two or more isomeric forms of a chemical compound


  1. (foll by the genitive case of a specified constellation) a star in a constellation, usually the second brightestBeta Persei

second letter of the Greek alphabet, c.1300, from Greek, from Hebrew/Phoenician beth (see alphabet); used to designate the second of many things. Beta radiation is from 1899 (Rutherford). Beta particle is attested from 1904.


  1. blood (used as a subscript)

  1. The symbol for the elementboron


  1. The second letter of the Greek alphabet.
  2. The second item in a series or system of classification.
  3. A beta particle.
  4. A beta ray.


  1. Of or relating to the second position from a designated carbon atom in an organic molecule at which an atom or a radical may be substituted.
  2. Of or relating to an isomeric variation of a chemical compound, such as a stereoisomer.

  1. The symbol for boron.
  2. The symbol for magnetic field.


  1. A shiny, brittle, black metalloid element extracted chiefly from borax. It is a good electrical conductor at high temperatures and a poor conductor at low temperatures. Boron is necessary for the growth of land plants and is used in the preparation of soaps, abrasives, and hard alloys. It is also used in the control rods of nuclear reactors as a neutron absorber. Atomic number 5; atomic weight 10.811; melting point 2,300°C; sublimation point 2,550°C; specific gravity (crystal) 2.34; valence 3. See Periodic Table.
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