a

1 of 13

noun

ˈā 

plural a's or as ˈāz 

often capitalized, often attributive

1

a

: the 1st letter of the English alphabet

b

: a graphic representation of this letter

c

: a speech counterpart of orthographic a

2

: the sixth tone of a C-major scale

3

: a graphic device for reproducing the letter a

4

: one designated a especially as the first in order or class

5

a

: a grade rating a student's work as superior in quality

b

: one graded or rated with an A

6

: something shaped like the letter A

7

capitalized : the one of the four ABO blood groups characterized by the presence of antigens designated by the letter A and by the presence of antibodies against the antigens present in the B blood group

a

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indefinite article

ə,

for emphasis

(ˈ)ā 

Canadian

ˈa 

1

—used as a function word before singular nouns when the referent is unspecified

a man overboard

and before number collectives and some numbers

a dozen

2

: the same

birds of a feather

swords all of a length

3

a

—used as a function word before a singular noun followed by a restrictive modifier

a man who was here yesterday

b

: any

a person who is sick can't work

c

—used as a function word before a mass noun to denote a particular type or instance

a bronze made in ancient times

d

—used as a function word before a proper noun representing an example or type

the attractions of a Boston or a Cleveland

e

—used as a function word before a proper noun to indicate limited knowledge about the referent

a Mr. Smith called to inquire about the job

f

—used as a function word before a proper noun to distinguish the condition of the referent from a usual, former, or hypothetical condition

a triumphant Ms. Jones greeted her supporters

g

—used before the name of a day of the week to refer to one occurrence of it

Christmas falls on a Tuesday this year.

h

—used before the name of a person (such as a famous artist) when the name is being used to refer to something (such as a painting) created by that person

Her violin is a Stradivarius.

i

—used before a family name to show that someone is a member of that family

To be a Kennedy is to lead two lives …

—Margaret Carlson

4

—used as a function word with nouns to form adverbial phrases of quantity, amount, or degree

felt a bit tired

A vs. an: Usage Guide

In speech and writing a is used before a consonant sound.

a door

a human

Before a vowel sound an is usual

an icicle

an honor

but especially in speech a is used occasionally, more often in some dialects than in others.

a apple

a hour

a obligation

Before a consonant sound represented by a vowel letter a is usual

a one

a union

but an also occurs though less frequently now than formerly.

an unique

such an one

Before unstressed or weakly stressed syllables with initial h both a and an are used in writing.

a historic

an historic

In the King James Version of the Old Testament and occasionally in writing and speech an is used before h in a stressed syllable.

an huntress

an hundred

children are an heritage of the Lord

—Psalms 127:3 (King James Version)

a

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preposition (1)

ə,

also

(ˈ)ā 

1

: in, to, or for each

twice a week

2

chiefly dialectal : on, in, at

a

4 of 13

preposition (2)

ə

informal

: of

There are a lot a stairs, but the view at the top is absolutely beautiful.

—Auli'i Cravalho, quoted in The New York Times

—often attached to the preceding word

But I did kinda sorta secretly hope to one day be interviewed from Oprah Winfrey's yoga nook.

—Jennifer Senior

That's a whole lotta [=lot of] hypothesizin' without a whole lotta science.

—Rebecca Watson

a

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verb

ə,

(ˌ)a 

archaic

: have

I might a had husbands afore now …

—John Bunyan

Poor Sir William! never shall I forget how he looked whin my lady and he parted. I could a tould the reason, but I'd a cut my tongue out first.

—Anne Newport Royall

a

6 of 13

abbreviation (1)

1

absent

2

acceleration

3

acre

4

adult

5

alto

6

chemistry amorphous

—usually used in combination

a-Si

7

anode

8

answer

9

ante

10

anterior

11

are

12

area

13

atto-

14

author

a-

7 of 13

prefix (1)

ə

1

: on : in : at

abed

2

: in (such) a state or condition

afire

3

: in (such) a manner

aloud

4

: in the act or process of

gone a-hunting

atingle

a-

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prefix (2)

(ˈ)ā,

 also  (ˈ)a,

 or  (ˈ)ä

variants or an-

(ˈ)an

: not : without

asexual

—a- before consonants other than h and sometimes even before h, an- before vowels and usually before h

achromatic

ahistorical

anastigmatic

anhydrous

-a-

9 of 13

combining form

: replacing carbon especially in a ring

aza-

-a

10 of 13

noun suffix

ə

: oxide

silica

alumina

magnesia

A

11 of 13

abbreviation (2)

1

ace

2

adenine

3

ampere

A

12 of 13

symbol

argon

Å

13 of 13

abbreviation (3)

angstrom

Examples of a in a Sentence

Noun

a word that begins with an a

a word that begins with a

a song in the key of A

She got an A on the exam.

Word History

Etymology

Indefinite article

Middle English, from Old English ān one — more at one

Preposition (1)

Middle English, from Old English a-, an, on

Preposition (2)

Middle English, by contraction

Verb

Middle English, contraction of have

Prefix (1)

Middle English, from Old English

Prefix (2)

Latin & Greek; Latin, from Greek — more at un-

Combining form

perhaps from -a- in ring compounds such as thiazole (in which -a- is the initial of azole)

Noun suffix

New Latin, from -a (as in magnesia)

First Known Use

Noun

before the 12th century, in the meaning defined at sense 1a

Indefinite Article

before the 12th century, in the meaning defined at sense 1

Preposition (1)

before the 12th century, in the meaning defined at sense 2

Preposition (2)

15th century, in the meaning defined above

Verb

14th century, in the meaning defined above

Kids Definition

a

1 of 5 noun

ˈā 

plural a's or as

often capitalized

1

: the first letter of the English alphabet

2

: a musical note referred to by the letter A : the sixth tone of a C-major scale

3

: a grade rating a student's work as superior

a

2 of 5 indefinite article

ə 

(ˈ)ā

1

: someone or something unspecified

a man in the street

a dozen

2

: the same : one

two of a kind

birds of a feather

3

: of whatever kind : any

a student who works hard

—used in all senses before words beginning with a consonant sound compare an

a

3 of 5 preposition

ə 

(ˈ)ā

: in each : to each : for each

twice a week

one a piece

a-

4 of 5 prefix

ə

1

: on : in : at

abed

2

: in a specified state or condition

afire

3

: in a specified manner

aloud

4

: in the act or process of

gone a-hunting

a-

5 of 5 prefix

(ˈ)ā

variants or an-

(ˈ)an

: not : without

asexual

—a- before consonants other than h and sometimes before h, an- before vowels and usually before h

anhydrate

Etymology

Indefinite article

Old English ān "one"

Preposition

Old English a-, an, on "on"

Prefix

Old English a- "on, in, at"

Prefix

Greek a-, an- "not"

Medical Definition

a

1 of 4 abbreviation

1

about

2

absent

3

absolute

4

absorbency; absorbent

5

accommodation

6

acetum

7

acid; acidity

8

actin

9

active; activity

10

allergist; allergy

11

alpha

12

anode

13

answer

14

ante

15

anterior

16

aqua

17

area

18

artery

19

asymmetric; asymmetry

A

2 of 4 noun

ˈā 

: the one of the four ABO blood groups characterized by the presence of antigens designated by the letter A and by the presence of antibodies against the antigens present in the B blood group

A

3 of 4 abbreviation

1

adenine

2

ampere

Å

4 of 4 symbol

angstrom