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)
Definition for a (4 of 31)
a
1[ uh; when stressed ey ]
/ ə; when stressed eɪ /
indefinite article
Origin of a
1Middle 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.
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.
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
3Middle 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
4Middle English; phonetic variant of have
Definition for a (8 of 31)
Origin of a
5Middle English a, ha
Definition for a (9 of 31)
A
Definition for a (10 of 31)
A
Symbol.
Definition for a (11 of 31)
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-
1a 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).
Definition for a (14 of 31)
a-
2a reduced form of the Old English preposition of: akin; afresh; anew.
Origin of a-
2Middle English; see a3
Definition for a (15 of 31)
a-
3an 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).
Definition for a (16 of 31)
Definition for a (17 of 31)
a-
5variant of ad-, used: (1) before sc, sp, st (ascend) and (2) in words of French derivation (often with the sense of increase, addition): amass.
Definition for a (18 of 31)
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.
2From the Latin word ante
Definition for a (22 of 31)
a.
3Definition for a (23 of 31)
Origin of A.
1< Latin annō, ablative of annus
Definition for a (24 of 31)
Origin of A.
2From the Latin word ante
Definition for a (25 of 31)
A.
3Definition for a (26 of 31)
-a
1a plural ending of nouns borrowed from Greek and Latin: phenomena; criteria; data; errata; genera.
Definition for a (27 of 31)
-a
2a 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
3an ending of personal names forming feminines from masculines: Georgia; Roberta.
Origin of -a
3Definition for a (29 of 31)
-a
4a suffix designating the oxide of the chemical element denoted by the stem: alumina; ceria; thoria.
Origin of -a
4probably generalized from the -a of magnesia
Definition for a (30 of 31)
alpha
[ al-fuh ]
/ ˈæl fə /
noun
adjective
Origin of alpha
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
/ (eɪ) /
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 eɪ) /
determiner (indefinite article; used before an initial consonant)
British Dictionary definitions for a (3 of 14)
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)
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-
1before 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-
2prefix
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)
- involving or relating to helium-4 nucleian alpha particle
- relating to one of two or more allotropes or crystal structures of a solidalpha iron
- 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)
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
[ ăl′fə ]
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.