noun, plural A’s or As, a’s or as.

  1. the first letter of the English alphabet, a vowel.
  2. any spoken sound represented by the letter A or a, as in bake, hat, father, or small.
  3. something having the shape of an A.
  4. a written or printed representation of the letter A or a.
  5. a device, as a printer’s type, for reproducing the letter A or a.

  1. from A to Z, from beginning to end; thoroughly; completely: He knows the Bible from A to Z.
  2. not know from A to B, to know nothing; be ignorant.


  1. are; ares.

Symbol, Logic.

  1. universal affirmative.

indefinite article

  1. not any particular or certain one of a class or group: a man; a chemical; a house.
  2. a certain; a particular: one at a time; two of a kind; A Miss Johnson called.
  3. another; one typically resembling: a Cicero in eloquence; a Jonah.
  4. one (used before plural nouns that are preceded by a quantifier singular in form): a hundred men (compare hundreds of men); a dozen times (compare dozens of times).
  5. indefinitely or nonspecifically (used with adjectives expressing number): a great many years; a few stars.
  6. one (used before a noun expressing quantity): a yard of ribbon; a score of times.
  7. any; a single: not a one.


  1. each; every; per: ten cents a sheet; three times a day.


  1. Pronunciation Spelling. a reduced, unstressed form of of (often written as part of a single, unhyphenated word): cloth a gold; time a day; kinda; sorta.

auxiliary verb Pronunciation Spelling.

  1. a reduced, unstressed form of auxiliary have following some modals, as might, should, could, would, and must (usually written as part of a single, unhyphenated word): We shoulda gone.

pronoun British Dialect.

  1. he.
  2. she.
  3. it.
  4. they.
  5. I.
  1. Electricity. ampere; amperes.
  2. Physics. angstrom.
  3. answer.
  4. British. arterial (used with a road number to designate a major highway): Take the A525 to Ruthin.


  1. the first 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 excellent or superior.
  3. (sometimes lowercase)(in some school systems) a symbol designating the first semester of a school year.
  4. Music.
    1. the sixth tone in the scale of C major or the first 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 sixth tone of the scale of C major, called la.
    5. the tonality having A as the tonic note.
  5. Physiology. a major blood group, usually enabling a person whose blood is of this type to donate blood to persons of group A or AB and to receive blood from persons of O or A.Compare ABO system.
  6. (sometimes lowercase)the medieval Roman numeral for 50 or 500.Compare Roman numerals.
  7. Chemistry. (formerly) argon.
  8. Chemistry, Physics. mass number.
  9. Biochemistry.
    1. adenine.
    2. alanine.
  10. Logic. universal affirmative.
  11. British. a designation for a motion picture recommended as suitable for adults.Compare AA(def 5), U(def 6), X(def 9).
  12. a proportional shoe width size, narrower than B and wider than AA.
  13. a proportional brassiere cup size, smaller than B and larger than AA.
  14. a quality rating for a corporate or municipal bond, lower than AA and higher than BBB.

Symbol, Physics.

  1. angstrom.


  1. Scot.all: for a’ that.
  1. a reduced form of the Old English preposition on, meaning “on,” “in,” “into,” “to,” “toward,” preserved before a noun in a prepositional phrase, forming a predicate adjective or an adverbial element (afoot; abed; ashore; aside; away), or before an adjective (afar; aloud; alow), as a moribund prefix with a verb (acknowledge), and in archaic and dialectal use before a present participle in -ing (set the bells aringing); and added to a verb stem with the force of a present participle (ablaze; agape; aglow; astride; and originally, awry).
  1. a reduced form of the Old English preposition of: akin; afresh; anew.
  1. an old point-action prefix, not referring to an act as a whole, but only to the beginning or end: She arose (rose up). They abided by their beliefs (remained faithful to the end).
  1. variant of ab- before p and v: aperient; avert.
  1. variant of ad-, used: (1) before sc, sp, st (ascend) and (2) in words of French derivation (often with the sense of increase, addition): amass.
  1. variant of an-1 before a consonant, meaning “not,” “without”: amoral; atonal; achromatic.
  1. atomic (used in combination): A-bomb; A-plant.
  1. year.
  1. before.
  1. about.
  2. acre; acres.
  3. active.
  4. adjective.
  5. alto.
  6. ampere; amperes.
  7. anonymous.
  8. answer.
  9. are; ares.
  10. Baseball. assist; assists.
  1. year.
  1. before.
  1. Absolute.
  2. Academy.
  3. acre; acres.
  4. America.
  5. American.
  6. angstrom.
  7. answer.
  8. April.
  9. Artillery.
  1. a plural ending of nouns borrowed from Greek and Latin: phenomena; criteria; data; errata; genera.
  1. a feminine singular ending of nouns borrowed from Latin and Greek, also used in Neo-Latin coinages to Latinize bases of any origin, and as a Latin substitute for the feminine ending -ē of Greek words: anabaena; cinchona; pachysandra.
  1. an ending of personal names forming feminines from masculines: Georgia; Roberta.
  1. a suffix designating the oxide of the chemical element denoted by the stem: alumina; ceria; thoria.


  1. the first letter of the Greek alphabet (A, α).
  2. the vowel sound represented by this letter.
  3. the first; beginning.
  4. (initial capital letter)Astronomy. used to designate the brightest star in a constellation.
  5. Chemistry. one of two or more isomeric compounds.
  6. the first in a series of related items: frequently used in chemistry and physics.
  7. Chiefly British. a mark or grade corresponding to an A.Compare beta(def 8), gamma(def 9).


    1. (of an animal) having the highest rank in a dominance hierarchy: the alpha female of an elephant pack.
    2. being the most dominant, powerful, or assertive person in a particular group.

    See also alpha male.

  1. alphabetical: Put the files in alpha order.
  2. Chemistry. pertaining or linked to the carbon atom closest to a particular group in an organic molecule.


  1. , 1502–72,Italian painter.

noun plural a’s, A’s or As

  1. the first letter and first vowel of the modern English alphabet
  2. any of several speech sounds represented by this letter, in English as in take, bag, calm, shortage, or cobra
  3. Also called: alphathe first in a series, esp the highest grade or mark, as in an examination
  4. from A to Zfrom start to finish, thoroughly and in detail

determiner (indefinite article; used before an initial consonant)

  1. used preceding a singular countable noun, if the noun is not previously specified or knowna dog; a terrible disappointment
  2. used preceding a proper noun to indicate that a person or thing has some of the qualities of the one nameda Romeo; a Shylock
  3. used preceding a noun or determiner of quantitya cupful; a dozen eggs; a great many; to read a lot
  4. used preceding a noun indicating a concrete or abstract thing capable of being dividedhalf a loaf; a quarter of a minute
  5. (preceded by once, twice, several times, etc) each or every; peronce a day; fifty pence a pound
  6. a certain; oneto change policy at a stroke; a Mr Jones called
  7. (preceded by not)any at allnot a hope


  1. an informal or dialect word for have they’d a said if they’d known


  1. (usually linked to the preceding noun) an informal form of of sorta sad; a kinda waste

symbol for

  1. acceleration
  2. are(s) (metric measure of land)
  3. atto-
  4. chess See algebraic notation

symbol for

  1. music
    1. a note having a frequency of 440 hertz (A above middle C) or this value multiplied or divided by any power of 2; the sixth 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. a human blood type of the ABO group, containing the A antigen
  3. (in Britain) a major arterial roadthe A3 runs from London to Portsmouth
  4. (formerly, in Britain)
    1. a film certified for viewing by anyone, but which contains material that some parents may not wish their children to see
    2. (as modifier)an A film
  5. mass number
  6. the number 10 in hexadecimal notation
  7. cardsace
  8. chemargon (now superseded by Ar)
  9. ampere(s)
  10. Also: atampere-turn
  11. absolute (temperature)
  12. (in circuit diagrams) ammeter
  13. area
  14. (in combination)atomican A-bomb; an A-plant
  15. chemaffinity
  16. biochemadenine
  17. logica universal affirmative categorical proposition, such as all men are mortal: often symbolized as SaPCompare E, I 2, O 1
    1. a person whose job is in top management, or who holds a senior administrative or professional position
    2. (as modifier)an A worker See also occupation groupings

abbreviation for

  1. Austria (international car registration)

symbol for

  1. angstrom unit


  1. not; without; opposite toatonal; asocial


  1. on; in; towardsafoot; abed; aground; aback
  2. literary, orarchaic(used before a present participle)in the act or process ofcome a-running; go a-hunting
  3. in the condition or state ofafloat; alive; asleep

abbreviation for

  1. acre(s) or acreage
  2. America(n)
  3. answer


  1. the first letter in the Greek alphabet (Α, α), a vowel transliterated as a
  2. Britishthe highest grade or mark, as in an examination
  3. (modifier)
    1. involving or relating to helium-4 nucleian alpha particle
    2. relating to one of two or more allotropes or crystal structures of a solidalpha iron
    3. relating to one of two or more isomeric forms of a chemical compound, esp one in which a group is attached to the carbon atom to which the principal group is attached
  4. (modifier)denoting the dominant person or animal in a groupthe alpha male


  1. Il, real name Agnolo di Cosimo . 1503–72, Florentine mannerist painter


  1. Scot variants of all


  1. (foll by the genitive case of a specified constellation)usually the brightest star in a constellationAlpha Centauri
  2. communicationsa code word for the letter a
1indefinite article, mid-12c., a variation of Old English an (see an) in which the -n- began to disappear before consonants, a process mostly complete by mid-14c. The -n- also was retained before words beginning with a sounded -h- until c.1600; it still is retained by many writers before unaccented syllables in h- or (e)u-, but is now no longer normally spoken as such. The -n- also lingered (especially in southern England dialect) before -w- and -y- through 15c.

2as in twice a day, etc., from Old English an “on,” in this case “on each.” The sense was extended from time to measure, price, place, etc. The habit of tacking a onto a gerund (as in a-hunting we will go) died out 18c.

3prefix meaning “not,” from Greek a-, an- “not,” from PIE root *ne “not” (see un-).

n.c.1300, from Latin alpha, from Greek alpha, from Hebrew or Phoenician aleph (see aleph). The Greeks added -a because Greek words cannot end in most consonants. Sense of “beginning of anything” is from late 14c., often paired with omega (last letter in the Greek alphabet) as “the end.” Sense of “first in a sequence” is from 1620s. Alpha male was in use by c.1960 among scientists studying animals; applied to humans in society from c.1992.

1in native (derived from Old English) words, it most commonly represents Old English an “on” (see a (2)), as in alive, asleep, abroad, afoot, etc., forming adjectives and adverbs from nouns; but it also can be Middle English of, as in anew, abreast (1590s); or a reduced form of Old English past participle prefix ge-, as in aware; or the Old English intensive a-, as in arise, awake, ashame, marking a verb as momentary, a single event. In words from Romanic languages, often it represents Latin ad- “to, at.”
2prefix meaning “not,” from Latin a-, short for ab “away from” (e.g. avert), or its cognate, Greek a-, short for apo “away from, from,” both cognate with Sanskrit apa “away from,” Gothic af, Old English of (see apo-).


  1. area
  2. asymmetrical
  3. specific absorption coefficient
  4. systemic arterial blood (used as a subscript)
  5. total acidity


  1. absorbance
  2. alveolar gas (used as a subscript)
  3. adenine
  4. AMP (in polynucleotides)
  5. ampere
  6. angstrom
  7. area


  1. The first letter of the Greek alphabet.
  2. The first one in a series; the beginning.
  3. The first position from a designated carbon atom in an organic molecule at which an atom or radical group may be substituted.


  1. Characterizing the atom or radical group that is closest to the functional group of atoms in an organic molecule.
  2. Relating to one of two or more closely related substances, as in stereoisomers.
  3. Relating to or characterizing a polypeptide chain that is one of five types of heavy chains present in immunoglobins.


  1. Without; not:acellular.


  1. angstrom
  1. Abbreviation of adenine, ampere, angstrom, area
  1. Abbreviation of angstrom
  1. A prefix meaning “without” or “not” when forming an adjective (such as amorphous, without form, or atypical, not typical), and “absence of” when forming a noun (such as arrhythmia, absence of rhythm). Before a vowel or h it becomes an- (as in anhydrous, anoxia).
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