a
1 Americanindefinite article
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not any particular or certain one of a class or group.
a man; a chemical; a house.
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a certain; a particular.
one at a time; two of a kind; A Miss Johnson called.
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another; one typically resembling.
a Cicero in eloquence; a Jonah.
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one (used before plural nouns that are preceded by a quantifier singular in form): a hundred men (comparehundreds of men ); a dozen times (comparedozens of times ).
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indefinitely or nonspecifically (used with adjectives expressing number).
a great many years; a few stars.
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one (used before a noun expressing quantity).
a yard of ribbon; a score of times.
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any; a single.
not a one.
preposition
preposition
auxiliary verb
abbreviation
noun
plural
A's, As, a's, as-
the first letter of the English alphabeta vowel.
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any spoken sound represented by the letter A or a, as in bakehatfather, or small.
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something having the shape of an A .
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a written or printed representation of the letter A or a.
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a deviceas a printer's typefor reproducing the letter A or a.
idioms
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not know from A to B, to know nothing; be ignorant.
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from A to Z, from beginning to end; thoroughly; completely.
He knows the Bible from A to Z.
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the first in order or in a series.
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Sometimes a
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(in some grading systems) a grade or markas in school or collegeindicating the quality of a student's work as excellent or superior.
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(in some school systems) a symbol designating the first semester of a school year.
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Music.
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the sixth tone in the scale of C major or the first tone in the relative minor scaleA minor.
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a stringkeyor pipe tuned to this tone.
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a written or printed note representing this tone.
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(in the fixed system of solmization) the sixth tone of the scale of C majorcalled la.
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the tonality having A as the tonic note.
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Physiology. a major blood groupusually 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.
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Sometimes a the medieval Roman numeral for 50 or 500.
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Chemistry. (formerly) argon.
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ChemistryPhysics. mass number.
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Biochemistry.
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Logic. Also a universal affirmative.
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British. a designation for a motion picture recommended as suitable for adults.
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a proportional shoe width sizenarrower than B and wider than AA.
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a proportional brassiere cup sizesmaller than B and larger than AA.
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a quality rating for a corporate or municipal bondlower than AA and higher than BBB.
adjective
abbreviation
abbreviation
abbreviation
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about.
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acre; acres.
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active.
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adjective.
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alto.
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ampere; amperes.
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anonymous.
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answer.
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are; ares.
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Baseball. assist; assists.
abbreviation
abbreviation
abbreviation
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Absolute.
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Academy.
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acre; acres.
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America.
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American.
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angstrom.
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answer.
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April.
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Artillery.
symbol
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music
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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
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a keystringor pipe producing this note
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the major or minor key having this note as its tonic
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a human blood type of the ABO groupcontaining the A antigen
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(in Britain) a major arterial road
the A3 runs from London to Portsmouth
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a film certified for viewing by anyonebut which contains material that some parents may not wish their children to see
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( as modifier )
an A film
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mass number
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the number 10 in hexadecimal notation
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cards ace
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chem argon (now superseded by Ar )
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ampere(s)
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Also: at. ampere-turn
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absolute (temperature)
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(in circuit diagrams) ammeter
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area
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(in combination) atomic
an A-bomb
an A-plant
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chem affinity
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biochem adenine
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logic a universal affirmative categorical propositionsuch as all men are mortal: often symbolized as SaP Compare E I 2 O 1
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a person whose job is in top managementor who holds a senior administrative or professional position
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( as modifier ) See also occupation groupings
an A worker
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abbreviation
determiner
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used preceding a singular countable nounif the noun is not previously specified or known
a dog
a terrible disappointment
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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
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used preceding a noun or determiner of quantity
a cupful
a dozen eggs
a great many
to read a lot
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used preceding a noun indicating a concrete or abstract thing capable of being divided
half a loaf
a quarter of a minute
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each or every; per
once a day
fifty pence a pound
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a certain; one
to change policy at a stroke
a Mr Jones called
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(preceded by not) any at all
not a hope
symbol
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acceleration
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are(s) (metric measure of land)
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atto-
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chess See algebraic notation
noun
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the first letter and first vowel of the modern English alphabet
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any of several speech sounds represented by this letterin English as in takebagcalmshortage, or cobra
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Also called: alpha. the first in a seriesesp the highest grade or markas in an examination
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from start to finishthoroughly and in detail
abbreviation
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acre(s) or acreage
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America(n)
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answer
prefix
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on; in; towards
afoot
abed
aground
aback
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literary (used before a present participle) in the act or process of
come a-running
go a-hunting
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in the condition or state of
afloat
alive
asleep
symbol
prefix
verb
preposition
determiner
Grammar
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 sounda is used; before a vowel soundan : a booka rose; an applean opera. Problems arise occasionally when the following word begins with a vowel letter but actually starts with a consonant soundor 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 soundas 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 wordsthey 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 wordsthey 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 pronouncedas in a stressed syllable at the beginning of a wordit 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 historichistoricalheroic, and habitual, which begin with an unstressed syllable and often with a silent or weakly pronounced h, are commonly preceded by anespecially 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 anbut this use is increasingly old-fashioned. Although in some dialects an has yielded to a in all casesedited writing reflects usage as described above.
Etymology
Origin of a1
First recorded in 1200–50; Middle English; originally preconsonantal phonetic variant of an 1
Origin of a2
Originally Middle English a, preconsonantal variant of on ( a- 1 ); confused with a 1
Origin of a3
Middle English; unstressed preconsonantal variant of of 1
Origin of a4
First recorded in 1300–50; Middle English; a phonetic variant of have
Origin of a5
First recorded in 1200–50; Middle English aha
Origin of a-12
Middle Englishlate Old English; a 2nowadays
Origin of a-13
Middle English; a 3
Origin of a-14
Middle English; Old English a- (unstressed)ǣ-ā-ō- (stressed; abbwoof 1oakum )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- 4as in abridge
Origin of a-15
Middle English < Latin ā-a- (variant of ab- ab- ); in some words < French a- < Latin ab-, as in abridge
Origin of a-16
Middle Englishin 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
Origin of -a20
From Latin feminine ending -a, as Claudia, feminine of Claudius; -a 2
Origin of -a21
Probably generalized from the -a of magnesia
Origin of a.23
< Latin annō, ablative of annus
Origin of a.24
From the Latin word ante
Origin of A.26
< Latin annō, ablative of annus
Origin of A.27
From the Latin word ante
Definitions and idiom definitions from Dictionary.com Unabridgedbased on the Random House Unabridged Dictionary© Random HouseInc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 200220011995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
