a

noun

ˈā 

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 pronunciation, with its broad a's …

—H. L. Mencken

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

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

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Words Starting With a

Browse 22,515 words and phrases that start with the letter A, from aa to Azzazame.

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.

Word History

First Known Use

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

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

Old English ān "one"

Old English a-, an, on "on"

Old English a- "on, in, at"

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