aaaa

Definition(s) of “A”

a |ā; ə| ( an before a vowel sound) [called the indefinite article ]

adjective

1 used when referring to someone or something for the first time in a text or conversation : a man came out of the room | it has been an honor to have you | we need people with a knowledge of languages. Compare with the .

• used with units of measurement to mean one such unit : a hundred | a quarter of an hour.

• [with negative ] one single; any : I simply haven't a thing to wear.

• used when mentioning the name of someone not known to the speaker : a Mr. Smith telephoned.

• someone like (the name specified) : you're no better than a Hitler.

2 used to indicate membership of a class of people or things : he is a lawyer | this car is a BMW.

3 used when expressing rates or ratios; in, to, or for each; per : typing 60 words a minute | cost as much as eight dollars a dozen.

ORIGIN Middle English : weak form of Old English ān [one.]

USAGE 1 The article a can be pronounced either |ā|, when stressed ("He gave you a flower?"—that is, only one flower), or |ə|, when unstressed ("He gave you a flower ?"—that is, the emphasis is on flower, not on the number of flowers). The form an is used before words beginning with a vowel sound. 2 On the question of using a or an before words beginning with h, see also usage at an .

a- 1

prefix

not; without : atheistic | atypical.

ORIGIN from Greek.

a- 2

prefix

to; toward : aside | ashore.

• in a specified state or manner : asleep | aloud.

• in the process of (an activity) : a-hunting.

• on : afoot.

• in : nowadays.

ORIGIN Old English , unstressed form of on .

a- 3

prefix

variant spelling of ad- assimilated before sc, sp, and st (as in ascend, aspire, and astringent).

a- 4

prefix

1 of : anew. [ORIGIN: unstressed form of of ]

2 utterly : abash. [ORIGIN: from Anglo-Norman French (corresponding to Old French e-, es-), from Latin ex.]

-a 1

suffix forming:

1 ancient or Latinized modern names of animals and plants : primula.

2 names of oxides : baryta.

3 geographical names : Africa.

4 ancient or Latinized modern feminine forenames : Lydia.

5 nouns from Italian, Portuguese, and Spanish : duenna | stanza.

ORIGIN representing a Greek, Latin, or Romance feminine singular.

-a 2

suffix forming plural nouns:

1 from Greek or Latin neuter plurals corresponding to a singular in -um or -on (such as addenda, phenomena.)

2 in names (often from modern Latin) of zoological groups : Protista | Insectivora.

-a 3

suffix informal

1 of : coupla.

2 have : mighta.

3 to : oughta.

ORIGIN representing a casual pronunciation.

A 1 |ā| (also a)

noun ( pl. As or A's )

1 the first letter of the alphabet.

• denoting the first in a set of items, categories, sizes, etc.

• denoting the first of two or more hypothetical people or things : suppose A had killed B.

• the highest class of academic mark.

• ( a) Chess denoting the first file from the left, as viewed from white's side of the board.

• (usu. a ) the first fixed quantity in an algebraic expression.

• ( A) the human blood type (in the ABO system) containing the A agglutinogen and lacking the B.

2 a shape like that of a capital A : [in combination ] an A-shape. See also A-frame , A-line .

3 Music the sixth note of the diatonic scale of C major.

• a key based on a scale with A as its keynote.

PHRASES

from A to B from one's starting point to one's destination : most road atlases will get you from A to B.

from A to Z over the entire range; completely : make sure you understand the subject from A to Z.

A 2

abbreviation

• ace (used in describing play in bridge and other card games) : you cash AK of hearts.

• ampere(s).

• ( Å) ångstrom(s).

• answer : Q: What’s the senator’s zodiac sign? A: He’s a Leo.

• (in personal ads) Asian.

• a dry cell battery size.

• Brit., informal A level.

ampere |ˈamˌpi(ə)r| (abbr.: A)

noun

a unit of electric current equal to a flow of one coulomb per second. • The SI base unit of electric current, 1 ampere is precisely defined as that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in a vacuum, would produce between these conductors a force of 2 × 10 −7 newton per meter.

ORIGIN late 19th cent.: named after A. M. Ampère .