variants
often A
plural a's; often A's or as; often As
ˈāz 
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
… the so-called Boston pronunciationwith its broad a's …—
H. L. Mencken
H. L. Mencken2
: 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
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
1
—used as a function word before singular nouns when the referent is unspecified
A man walked by.
heard a shout
and before number collectives and some numbersa dozen
a thousand
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 person who saw it happen
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 plastic used in packaging
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 usualformeror 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
My birthday 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
Margaret Carlson4
—used as a function word with nouns to form adverbial phrases of quantityamountor 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 occasionallymore 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)
Psalms 127:3 (King James Version)
ə
also
(ˈ)ā
ə
informal
: of
There are a lot a stairsbut the view at the top is absolutely beautiful.—Auli'i Cravalho quoted in The New York Times
—often attached to the preceding wordAuli'i Cravalho quoted in The New York TimesBut I did kinda sorta secretly hope to one day be interviewed from Oprah Winfrey's yoga nook.—Jennifer Senior
Jennifer SeniorThat's a whole lotta [=lot of] hypothesizin' without a whole lotta science.—Rebecca Watson
Rebecca Watson
archaic
: have
I might a had husbands afore now …—John Bunyan
John BunyanPoor Sir William! never shall I forget how he looked whin my lady and he parted. I could a tould the reasonbut I'd a cut my tongue out first.—Anne Newport Royall
Anne Newport Royall1
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
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
(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 han- before vowels and usually before hachromatic
ahistorical
anastigmatic
anhydrous
: replacing carbon especially in a ring
aza-
ə
: oxide
silica
alumina
magnesia
1
ace
2
adenine
3
ampere
argon
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.
Recent Examples on the Web
Mike WallSpace.com22 Nov. 2025
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Preposition
Spaceflight caused a 20% reduction in chlorophyll athe main pigment involved in photosynthesisbut the spores seemed to be healthy despite that dropthe team found.
—Mike WallSpace.com22 Nov. 2025
Cite this Entry
“A.” Merriam-Webster.com DictionaryMerriam-Websterhttps://www.merriam-webster.com/dictionary/a. Accessed 6 Mar. 2026.
Copy CitationKids 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
3 of 5 preposition
ə
(ˈ)ā
: in each : to each : for each
twice a week
one a piece
a-
4 of 5 prefixə
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 han- before vowels and usually before hanhydrate
Etymology
Indefinite article
Old English ān "one"
Preposition
Old English a-, an, on "on"
Prefix
Old English a- "oninat"
Prefix
Greek a-an- "not"
Medical Definition
a
1 of 4 abbreviation1
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 abbreviation1
adenine
2
ampere
Å
4 of 4 symbol
angstrom
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