a

noun, often capitalized, often attributive \ ˈā \

Updated on: 15 Nov 2017

Definition of a

plural a's or as play \ˈāz\

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

See a defined for English-language learners

See a defined for kids

Examples of a in a Sentence

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.

First Known Use of a

before 12th century

Other Alphabet Terms

cuneiform, linear, minuscule, pictograph, rune, symbology, wedge

a

indefinite article \ ə , (ˈ)ā , Canadian ˈa \

Definition of a

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 man 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

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

felt a bit tired

a vs. an

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)

Origin and Etymology of a

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

NEW! Time Traveler

First Known Use: before 12th century

See Words from the same year

a

preposition \ ə also (ˈ)ā \

Definition of a

1 : in, to, or for each

twice a week

2 chiefly dialectal : on, in, at

a vs. an

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)

Origin and Etymology of a

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

NEW! Time Traveler

First Known Use: before 12th century

See Words from the same year

a

preposition \ ə \

Definition of a

: of —often attached to the preceding word

kinda

lotta

Origin and Etymology of a

Middle English, by contraction

NEW! Time Traveler

First Known Use: 15th century

See Words from the same year

a

verb \ ə , (ˌ)a \

Definition of a

archaic

: have

I might a had husbands afore now
—John Bunyan

Origin and Etymology of a

Middle English, contraction of have

NEW! Time Traveler

First Known Use: 14th century

See Words from the same year

a

abbreviation

Definition of a

1 absent

2 acceleration

3 acre

4 adult

5 alto

6 anode

7 answer

8 ante

9 anterior

10 are

11 area

12 atto-

13 author

a-

prefix \ ə \

Definition of a-

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

Origin and Etymology of a-

Middle English, from Old English

a-

prefix \ (ˈ)ā also (ˈ)a or (ˈ)ä \

variants: or an- \(ˈ)an\

Definition of a-

: 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

Origin and Etymology of a-

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

-a-

combining form

Definition of -a-

: replacing carbon especially in a ring

aza-

Origin and Etymology of -a-

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

-a

noun suffix \ ə \

Definition of -a

: oxide

silica

Origin and Etymology of -a

New Latin, from -a (as in magnesia)

A

abbreviation

Definition of A

1 ace

2 adenine

3 ampere

A

symbol

Definition of A

argon

Å

abbreviation

Definition of Å

angstrom unit

A Defined for English Language Learners

a

noun

Definition of a for English Language Learners

: the first letter of the English alphabet
: a musical note or key referred to by the letter A : the sixth tone of a C-major scale
: a grade that is given to a student for doing excellent work

a

indefinite article

Definition of a for English Language Learners

—used before singular nouns when the person or thing is being mentioned for the first time
—used like one before number words like hundred, thousand, etc.
—used like one before number words like third, fortieth, etc.

A Defined for Kids

a

noun, often capitalized \ ˈā \

Definition of a for Students

plural a's or as \ˈāz\

1 : the first letter of the English alphabet

2 : a grade that shows a student's work is excellent

3 : a musical note referred to by the letter A

a

indefinite article \ ə , ˈā \

Definition of a for Students

1 : someone or something being mentioned for the first time

There's a dog in the yard.

2 : the same

two of a kind

3 : ¹any 1

It's hard for a person to understand.

4 : for or from each

an apple a day

The new theater charges ten dollars a person.

5 : ²one 3

a dozen doughnuts

a week

This is a third the size of that.

Hint: A is used before words that do not begin with a vowel sound.

a-

prefix \ ə \

Definition of a- for Students

1 : on : in : at

abed

2 : in (such) a state, condition, or manner

afire

aloud

3 : in the act or process of

gone a-hunting

Medical Dictionary

a

abbreviation

medical Definition of a

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

noun \ ˈā \

medical Definition of A

: 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

abbreviation

medical Definition of A

1 adenine

2 ampere

Å

symbol

medical Definition of Å

angstrom

Learn More about a

See words that rhyme with a Spanish Central: Translation of a Nglish: Translation of a for Spanish speakers Britannica English: Translation of a for Arabic speakers

Seen and Heard

What made you want to look up a? Please tell us where you read or heard it (including the quote, if possible).

show

a

Definition of a

Explore M-W

Examples of a in a Sentence

First Known Use of a

Other Alphabet Terms

a

Definition of a

a vs. an

Origin and Etymology of a

a

Definition of a

a vs. an

Origin and Etymology of a

a

Definition of a

Origin and Etymology of a

a

Definition of a

Origin and Etymology of a

a

Definition of a

a-

Definition of a-

Origin and Etymology of a-

a-

Definition of a-

Origin and Etymology of a-

-a-

Definition of -a-

Origin and Etymology of -a-

-a

Definition of -a

Origin and Etymology of -a

A

Definition of A

A

Definition of A

Å

Definition of Å

A Defined for English Language Learners

a

Definition of a for English Language Learners

a

Definition of a for English Language Learners

A Defined for Kids

a

Definition of a for Students

a

Definition of a for Students

a-

Definition of a- for Students

Medical Dictionary

a

medical Definition of a

A

medical Definition of A

A

medical Definition of A

Å

medical Definition of Å

Learn More about a

Seen and Heard

Love words? Need even more definitions?

Love words? Need even more definitions?

Words at Play

Ask the Editors

Word Games

Trending: Franks Resigns Amid 'Surrogacy' Scandal

'Wreck' and 'Reckless': Accidents Happen

Intact Latin Quiz

It's a Living: Last Names That Started as Jobs

Words of the Year: 1066