A, a

[ ey ]
/ eɪ /

noun, plural A's or As, a's or as.

the first letter of the English alphabet, a vowel.
any spoken sound represented by the letter A or a, as in bake, hat, father, or small.
something having the shape of an A.
a written or printed representation of the letter A or a.
a device, as a printer's type, for reproducing the letter A or a.

Idioms

    from A to Z, from beginning to end; thoroughly; completely: He knows the Bible from A to Z.
    not know from A to B, to know nothing; be ignorant.

Definition for a (2 of 31)

a


Measurements.

are; ares.

Definition for a (3 of 31)

a


Symbol, Logic.

Definition for a (4 of 31)

a

1
[ uh; when stressed ey ]
/ ə; when stressed eɪ /

indefinite article

Origin of a

1
Middle English; orig. preconsonantal phonetic variant of an1

Usage note

In both spoken and written English the choice of a1 or an1 is determined by the initial sound of the word that follows. Before a consonant sound, a is used; before a vowel sound, an : a book, a rose; an apple, an opera. Problems arise occasionally when the following word begins with a vowel letter but actually starts with a consonant sound, or vice versa. Some words beginning with the vowel letter u and all words beginning with the vowel letters eu are pronounced with a beginning consonant sound, as if the first letter were y : a union; a European. Some other spellings that begin with a vowel letter may also stand for an initial consonant sound: a ewe; a ewer. The words one and once and all compounds of which they are the first element begin with a w sound: a one-room apartment; a once-famous actor.
The names of the consonant letters f, h, l, m, n, r, s, and x are pronounced with a beginning vowel sound. When these letters are used as words or to form words, they are preceded by an : to rent an L-shaped studio; to fly an SST. The names of the vowel letter u and the semivowel letters w and y are pronounced with a beginning consonant sound. When used as words, they are preceded by a : a U-turn; The plumber installed a Y in the line.
In some words beginning with the letter h, the h is not pronounced; the words actually begin with a vowel sound: an hour; an honor. When the h is strongly pronounced, as in a stressed syllable at the beginning of a word, it is preceded by a : a history of the Sioux; a hero sandwich. (In former times an was used before strongly pronounced h in a stressed first syllable: an hundred. ) Such adjectives as historic, historical, heroic, and habitual, which begin with an unstressed syllable and often with a silent or weakly pronounced h, are commonly preceded by an, especially in British English. But the use of a rather than an is widespread in both speech and writing: a historical novel; a habitual criminal. Hotel and unique are occasionally preceded by an, but this use is increasingly old-fashioned. Although in some dialects an has yielded to a in all cases, edited writing reflects usage as described above.

Definition for a (5 of 31)

a

2
[ uh; when stressed ey ]
/ ə; when stressed eɪ /

preposition

each; every; per: ten cents a sheet; three times a day.

Origin of a

2
orig. Middle English a, preconsonantal variant of on (see a-1); confused with a1

Definition for a (6 of 31)

a

3
[ uh ]
/ ə /

preposition

Pronunciation Spelling. a reduced, unstressed form of of (often written as part of a single, unhyphenated word): cloth a gold; time a day; kinda; sorta.

Origin of a

3
Middle English; unstressed preconsonantal variant of of1

Definition for a (7 of 31)

a

4
[ uh ]
/ ə /

auxiliary verb Pronunciation Spelling.

a reduced, unstressed form of auxiliary have following some modals, as might, should, could, would, and must (usually written as part of a single, unhyphenated word): We shoulda gone.
Compare of2.

Origin of a

4
Middle English; phonetic variant of have

Definition for a (8 of 31)

a

5
[ uh, a, ah ]
/ ə, æ, ɑ /

pronoun British Dialect.

Origin of a

5
Middle English a, ha

Definition for a (9 of 31)

A


Electricity. ampere; amperes.
Physics. angstrom.
British. arterial (used with a road number to designate a major highway): Take the A525 to Ruthin.

Definition for a (10 of 31)

A


Symbol.

Definition for a (11 of 31)

Å


Symbol, Physics.

Definition for a (12 of 31)

a'

or a

[ ah, aw ]
/ ɑ, ɔ /

adjective

Scot. all: for a' that.

Definition for a (13 of 31)

a-

1

a reduced form of the Old English preposition on, meaning “on,” “in,” “into,” “to,” “toward,” preserved before a noun in a prepositional phrase, forming a predicate adjective or an adverbial element (afoot; abed; ashore; aside; away), or before an adjective (afar; aloud; alow), as a moribund prefix with a verb (acknowledge), and in archaic and dialectal use before a present participle in -ing (set the bells aringing); and added to a verb stem with the force of a present participle (ablaze; agape; aglow; astride; and originally, awry).

Origin of a-

1
Middle English, late Old English; cf. a2, nowadays

Definition for a (14 of 31)

a-

2

a reduced form of the Old English preposition of: akin; afresh; anew.

Origin of a-

2
Middle English; see a3

Definition for a (15 of 31)

a-

3

an old point-action prefix, not referring to an act as a whole, but only to the beginning or end: She arose (rose up). They abided by their beliefs (remained faithful to the end).

Origin of a-

3
Middle English; Old English a- (unstressed), ǣ-, ā-, ō- (stressed; see abb, woof1, oakum), rarely or- (see ordeal) ≪ Germanic *uz- < unstressed Indo-European *uss- < *ud-s, akin to out; in some cases confused with a-4, as in abridge

Definition for a (16 of 31)

a-

4

variant of ab- before p and v: aperient; avert.

Origin of a-

4
Middle English < Latin ā-, a- (variant of ab- ab-); in some words < French a- < Latin ab-, as in abridge

Definition for a (17 of 31)

a-

5

variant of ad-, used: (1) before sc, sp, st (ascend) and (2) in words of French derivation (often with the sense of increase, addition): amass.

Origin of a-

5
Middle English, in some words < Middle French a- < Latin ad- prefix or ad preposition (see ad-), as in abut; in others < Latin a- (variant of ad- ad-), as in ascend

Definition for a (18 of 31)

a-

6

variant of an-1 before a consonant, meaning “not,” “without”: amoral; atonal; achromatic.

Definition for a (19 of 31)

A-


atomic (used in combination): A-bomb; A-plant.

Definition for a (20 of 31)

Origin of a.

1
< Latin annō, ablative of annus

Definition for a (21 of 31)

Origin of a.

2
From the Latin word ante

Definition for a (22 of 31)

a.

3

Definition for a (23 of 31)

Origin of A.

1
< Latin annō, ablative of annus

Definition for a (24 of 31)

Origin of A.

2
From the Latin word ante

Definition for a (25 of 31)

Definition for a (26 of 31)

-a

1

a plural ending of nouns borrowed from Greek and Latin: phenomena; criteria; data; errata; genera.

Definition for a (27 of 31)

-a

2

a feminine singular ending of nouns borrowed from Latin and Greek, also used in Neo-Latin coinages to Latinize bases of any origin, and as a Latin substitute for the feminine ending -ē of Greek words: anabaena; cinchona; pachysandra.

Definition for a (28 of 31)

-a

3

an ending of personal names forming feminines from masculines: Georgia; Roberta.

Origin of -a

3
< L feminine -a (see -a2), as Claudia, feminine of Claudius

Definition for a (29 of 31)

-a

4

a suffix designating the oxide of the chemical element denoted by the stem: alumina; ceria; thoria.

Origin of -a

4
probably generalized from the -a of magnesia

Definition for a (30 of 31)

alpha

[ al-fuh ]
/ ˈæl fə /

noun

adjective

Origin of alpha

< Latin < Greek álpha < Semitic; cf. aleph

Definition for a (31 of 31)

Bronzino

[ brawn-dzee-naw ]
/ brɔnˈdzi nɔ /

noun

A·gno·lo (di Co·si·mo di Ma·ria·no) [ah-nyaw-law dee kaw-zee-maw dee mah-ryah-naw] /ˈɑ nyɔ lɔ di ˈkɔ zi mɔ di mɑˈryɑ nɔ/, 1502–72, Italian painter.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for a (1 of 14)

a

A

/ () /

noun plural a's, A's or As

the first letter and first vowel of the modern English alphabet
any of several speech sounds represented by this letter, in English as in take, bag, calm, shortage, or cobra
Also called: alpha the first in a series, esp the highest grade or mark, as in an examination
from A to Z from start to finish, thoroughly and in detail

British Dictionary definitions for a (2 of 14)

a

1
/ (ə, stressed or emphatic ) /

determiner (indefinite article; used before an initial consonant)

Compare an 1See the 1

British Dictionary definitions for a (3 of 14)

a

2
/ (ə) /

verb

an informal or dialect word for have they'd a said if they'd known

British Dictionary definitions for a (4 of 14)

a

3
/ (ə) /

preposition

(usually linked to the preceding noun) an informal form of of sorta sad; a kinda waste

British Dictionary definitions for a (5 of 14)

a

4

symbol for

acceleration
are(s) (metric measure of land)
atto-

British Dictionary definitions for a (6 of 14)

A


symbol for

abbreviation for

Austria (international car registration)

Word Origin for A

from Latin a (ffirmo) I affirm

British Dictionary definitions for a (7 of 14)

Å


symbol for

angstrom unit

British Dictionary definitions for a (8 of 14)

a-

1

before a vowel an-


prefix

not; without; opposite toatonal; asocial

Word Origin for a-

from Greek a-, an- not, without

British Dictionary definitions for a (9 of 14)

a-

2

prefix

on; in; towardsafoot; abed; aground; aback
literary, or archaic (used before a present participle) in the act or process ofcome a-running; go a-hunting
in the condition or state ofafloat; alive; asleep

British Dictionary definitions for a (10 of 14)

A.


abbreviation for

acre(s) or acreage
America(n)
answer

British Dictionary definitions for a (11 of 14)

alpha

/ (ˈælfə) /

noun

the first letter in the Greek alphabet (Α, α), a vowel transliterated as a
British the highest grade or mark, as in an examination
(modifier)
  1. involving or relating to helium-4 nucleian alpha particle
  2. relating to one of two or more allotropes or crystal structures of a solidalpha iron
  3. relating to one of two or more isomeric forms of a chemical compound, esp one in which a group is attached to the carbon atom to which the principal group is attached
(modifier) denoting the dominant person or animal in a groupthe alpha male

Word Origin for alpha

via Latin from Greek, of Phoenician origin; related to Hebrew āleph, literally: ox

British Dictionary definitions for a (12 of 14)

Bronzino

/ (bronˈdziːno) /

noun

Il, real name Agnolo di Cosimo . 1503–72, Florentine mannerist painter

British Dictionary definitions for a (13 of 14)

a'

aa or aw

/ (ɔː) /

determiner

Scot variants of all

British Dictionary definitions for a (14 of 14)

Alpha

/ (ˈælfə) /

noun

(foll by the genitive case of a specified constellation) usually the brightest star in a constellationAlpha Centauri
communications a code word for the letter a
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for a (1 of 5)

a


abbr.

area
asymmetrical
specific absorption coefficient
systemic arterial blood (used as a subscript)
total acidity

Medicine definitions for a (2 of 5)

A


abbr.

Medicine definitions for a (3 of 5)

alpha

[ ălfə ]

n.

The first letter of the Greek alphabet.
The first one in a series; the beginning.
The first position from a designated carbon atom in an organic molecule at which an atom or radical group may be substituted.

adj.

Characterizing the atom or radical group that is closest to the functional group of atoms in an organic molecule.
Relating to one of two or more closely related substances, as in stereoisomers.
Relating to or characterizing a polypeptide chain that is one of five types of heavy chains present in immunoglobins.

Medicine definitions for a (4 of 5)

a-


pref.

Without; not:acellular.

Medicine definitions for a (5 of 5)

Å


abbr.

angstrom
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for a (1 of 3)

A


Abbreviation of adenine, ampere, angstrom, area

Science definitions for a (2 of 3)

Å


Abbreviation of angstrom

Science definitions for a (3 of 3)

a-


A prefix meaning “without” or “not” when forming an adjective (such as amorphous, without form, or atypical, not typical), and “absence of” when forming a noun (such as arrhythmia, absence of rhythm). Before a vowel or h it becomes an- (as in anhydrous, anoxia).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.