a

¹

[ uh; when stressed ey ]

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.

A

²

or a

[ ey ]

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.

a-

³

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 ).

-a

⁴

1. a plural ending of nouns borrowed from Greek and Latin:

   phenomena; criteria; data; errata; genera.

a.

⁵

abbreviation for

1. year.

A.

⁶

abbreviation for

1. year.

a

⁷

[ uh; when stressed ey ]

preposition

1. each; every; per:

   ten cents a sheet; three times a day.

A

⁸

abbreviation for

1. Electricity. ampere; amperes.
2. Physics. angstrom; angstroms.
3. answer.
4. British. arterial (used with a road number to designate a major highway):

   Take the A525 to Ruthin.

a-

⁹

1. a reduced form of the Old English preposition of: akin; afresh; anew.

-a

¹⁰

1. a feminine singular ending of nouns borrowed from Latin and Greek, also used in New Latin coinages to Latinize bases of any origin, and as a Latin substitute for the feminine ending - ē of Greek words: cinchona;

   anabaena;

   cinchona;

   pachysandra.

a.

¹¹

abbreviation for

1. before.

A.

¹²

abbreviation for

1. before.

a

¹³

[ uh ]

preposition

1. Informal. a reduced, unstressed form of of (often written as part of a single, unhyphenated word):

   cloth a gold; time a day; kinda; sorta.

A

¹⁴

Symbol.

1. the first in order or in a series.
2. Sometimes a.
   1. (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.
   2. (in some school systems) a symbol designating the first semester of a school year.
3. 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.
4. 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.
5. Sometimes a. the medieval Roman numeral for 50 or 500. Compare Roman numerals.
6. Chemistry. (formerly) argon.
7. Chemistry, Physics. mass number.
8. Biochemistry.
   1. adenine ( def ).
   2. alanine
9. Also a. Logic. universal affirmative.
10. British. a designation for a motion picture recommended as suitable for adults. Compare AA ²( def 5 ), U ⁵( def 6 ), X ³( def 9 ).
11. a proportional shoe width size, narrower than B and wider than AA.
12. a proportional brassiere cup size, smaller than B and larger than AA.
13. a quality rating for a corporate or municipal bond, lower than AA and higher than BBB.

a-

¹⁵

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).

-a

¹⁶

1. an ending of personal names forming feminines from masculines:

   Georgia; Roberta.

a.

¹⁷

abbreviation for

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.

A.

¹⁸

abbreviation for

1. Absolute.
2. Academy.
3. acre; acres.
4. America.
5. American.
6. angstrom.
7. answer.
8. April.
9. Artillery.

a

¹⁹

[ uh ]

auxiliary verb

, Informal.

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.

a-

²⁰

1. variant of ab- before p and v: aperient; avert.

-a

²¹

1. a suffix designating the oxide of the chemical element denoted by the stem:

   alumina; ceria; thoria.

a

²²

[ uh, a, ah ]

pronoun

, British Dialect.

1. he ¹.
2. she.
3. it ¹.
4. they.
5. I ².

a-

²³

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.

a

²⁴

abbreviation for

, Measurements.

1. are; ares.

a-

²⁵

1. variant of an- ¹ before a consonant, meaning “not,” “without”:

   amoral; atonal; achromatic.

Å

²⁶

Symbol, Physics.

1. angstrom.

a'

²⁷

or a

[ ah, aw ]

adjective

, Scots

1. all:

   for a' that.

A-

²⁸

1. atomic (used in combination):

   A-bomb; A-plant.

a

¹

/ ə /

preposition

1. (usually linked to the preceding noun) an informal form of of

   sorta sad

   a kinda waste

a-

²

prefix

1. not; without; opposite to

   atonal

   asocial

A.

³

abbreviation for

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

A

⁴

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 road

   the 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. cards ace
8. chem argon (now superseded by Ar )
9. ampere(s)
10. Alsoat ampere-turn
11. absolute (temperature)
12. (in circuit diagrams) ammeter
13. area
14. in combination atomic

    an A-bomb

    an A-plant

15. chem affinity
16. biochem adenine
17. logic a universal affirmative categorical proposition, such as all men are mortal: often symbolized as SaP Compare E I 2 O 1
18. 1. a person whose job is in top management, or who holds a senior administrative or professional position
    2. ( as modifier ) See also occupation groupings

       an A worker

abbreviation for

1. Austria (international car registration)

a

⁵

/ eɪ /

noun

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 calledalpha the first in a series, esp the highest grade or mark, as in an examination
4. from A to Z
   from start to finish, thoroughly and in detail

a-

⁶

prefix

1. on; in; towards

   aground

   aback

   afoot

   abed

2. literary.
   used before a present participle in the act or process of

   come a-running

   go a-hunting

3. in the condition or state of

   afloat

   alive

   asleep

Å

⁷

symbol for

1. angstrom unit

a

⁸

symbol for

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

a

⁹

/ ə; eɪ /

determiner

1. used preceding a singular countable noun, if the noun is not previously specified or known

   a 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 named

   a Romeo

   a Shylock

3. used preceding a noun or determiner of quantity

   a dozen eggs

   to read a lot

   a great many

   a cupful

4. used preceding a noun indicating a concrete or abstract thing capable of being divided

   half a loaf

   a quarter of a minute

5. preceded byonce, twice, several times, etc each or every; per

   once a day

   fifty pence a pound

6. a certain; one

   to change policy at a stroke

   a Mr Jones called

7. preceded by not any at all

   not a hope

a'

¹⁰

/ ɔː /

determiner

1. variants of all

a

¹¹

/ ə /

verb

1. an informal or dialect word for have

   they'd a said if they'd known

Å

¹

1. Abbreviation of angstrom

A

²

1. Abbreviation of adenine , ampere , angstrom , area

a–

³

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 ).

Grammar Note

In both spoken and written English the choice of a1 or an ¹ is determined by the initial sound of the word that follows. Before a consonant sound, a is used; before a vowel sound, an : a book, a rose; an apple, an opera. Problems arise occasionally when the following word begins with a vowel letter but actually starts with a consonant sound, or vice versa. Some words beginning with the vowel letter u and all words beginning with the vowel letters eu are pronounced with a beginning consonant sound, as if the first letter were y : a union; a European. Some other spellings that begin with a vowel letter may also stand for an initial consonant sound: a ewe; a ewer. The words one and once and all compounds of which they are the first element begin with a w sound: a one-room apartment; a once-famous actor. The names of the consonant letters f, h, l, m, n, r, s, and x are pronounced with a beginning vowel sound. When these letters are used as words or to form words, they are preceded by an : to rent an L-shaped studio; to fly an SST. The names of the vowel letter u and the semivowel letters w and y are pronounced with a beginning consonant sound. When used as words, they are preceded by a : a U-turn; The plumber installed a Y in the line. In some words beginning with the letter h, the h is not pronounced; the words actually begin with a vowel sound: an hour; an honor. When the h is strongly pronounced, as in a stressed syllable at the beginning of a word, it is preceded by a : a history of the Sioux; a hero sandwich. (In former times an was used before strongly pronounced h in a stressed first syllable: an hundred. ) Such adjectives as historic, historical, heroic, and habitual, which begin with an unstressed syllable and often with a silent or weakly pronounced h, are commonly preceded by an, especially in British English. But the use of a rather than an is widespread in both speech and writing: a historical novel; a habitual criminal. Hotel and unique are occasionally preceded by an, but this use is increasingly old-fashioned. Although in some dialects an has yielded to a in all cases, edited writing reflects usage as described above.

Word History and Origins

Origin of a¹

First recorded in 1200–50; Middle English; originally preconsonantal phonetic variant of an ¹

Origin of a²

Middle English, late Old English; a ², nowadays

Origin of a³

< Latin annō, ablative of annus

Origin of a⁴

< Latin annō, ablative of annus

Origin of a⁵

Originally Middle English a, preconsonantal variant of on ( a- ¹ ); confused with a ¹

Origin of a⁶

Middle English; a ³

Origin of a⁷

From the Latin word ante

Origin of a⁸

From the Latin word ante

Origin of a⁹

Middle English; unstressed preconsonantal variant of of ¹

Origin of a¹⁰

Middle English; Old English a- (unstressed), ǣ-, ā-, ō- (stressed; abb, woof ¹, oakum ), rarely or- ( ordeal ), ultimately from unattested Germanic uz- from unstressed Indo-European uss-, from ud-s (these latter two also unattested), akin to out; in some cases confused with a- ⁴, as in abridge

Origin of a¹¹

From Latin feminine ending -a, as Claudia, feminine of Claudius; -a ²

Origin of a¹²

First recorded in 1300–50; Middle English; a phonetic variant of have

Origin of a¹³

Middle English < Latin ā-, a- (variant of ab- ab- ); in some words < French a- < Latin ab-, as in abridge

Origin of a¹⁴

Probably generalized from the -a of magnesia

Origin of a¹⁵

First recorded in 1200–50; Middle English a, ha

Origin of a¹⁶

Middle English, in some words < Middle French a- < Latin ad- prefix or ad preposition ( ad- ), as in abut; in others < Latin a- (variant of ad- ad- ), as in ascend

Word History and Origins

Origin of a¹

from Greek a-, an- not, without

Origin of a²

from Latin a ( ffirmo ) I affirm

Idioms and Phrases

Idioms

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.

Example Sentences

To understand these associations on a cellular level, the researchers used air quality data collected by the Environmental Protection Agency to calculate study participants' average PM2.5 exposure.

From Science Daily

The immune performance of wild capuchin monkeys declines when the animals experience higher temperatures, and younger monkeys seem to be particularly vulnerable to heat, according to a University of Michigan study.

From Science Daily

Building on a decade of research, scientists from MIT and elsewhere have developed a new photonic chip that overcomes these roadblocks.

From Science Daily

Electrons exhibit both particle and wave-like properties -- they don't simply roll like a ball.

From Science Daily

Walker is currently a veterinary medical officer with the U.S.

From Science Daily

Related Words

• an