a

1 of 13

noun

plural a's or as ˈāz How to pronounce a (audio)
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

2 of 13

indefinite article

ə,
for emphasis
(ˈ)ā How to pronounce a (audio)
Canadian
ˈa How to pronounce a (audio)
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

3 of 13

preposition (1)

ə,
also
(ˈ)ā How to pronounce a (audio)
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

5 of 13

verb

ə,
(ˌ)a How to pronounce a (audio)
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-

8 of 13

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

Time Traveler
The first known use of a was before the 12th century

Dictionary Entries Near a

Cite this Entry

“A.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/a. Accessed 19 Mar. 2024.

Kids Definition

a

1 of 5 noun
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 How to pronounce a (audio)
(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 person who is sick can't work well
used in all senses before words beginning with a consonant sound
compare an

a

3 of 5 preposition
ə How to pronounce a (audio)
(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
: 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

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