A

Multiple Entries:
  A    a    -a    a-    ad-    ampere    angstrom  

Concise Oxford English Dictionary © 2008 Oxford University Press:
A1 (also a)

▶noun (pl. As or A's)

• 1 the first letter of the alphabet.

• 2 denoting the first, best, or most important in a set.

• 3 Music the sixth note of the diatonic scale of C major, having a standard frequency of 440 Hz.

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

– phrases
from A to B from one's starting point to one's destination.
from A to Z over the entire range.

Concise Oxford English Dictionary © 2008 Oxford University Press:
A2

▶abbreviation

• 1 (in card games) ace.

• 2 (in showing goals or points conceded) against.

• 3 ampere(s).

• 4 (Å) ångström(s).

• 5 answer.

• 6 (in names of sports clubs) Athletic.

• 7 attack (in designations of US aircraft types): an A-10.

• 8 Austria (international vehicle registration).

Concise Oxford English Dictionary © 2008 Oxford University Press:
a1 (an before a vowel sound)

▶determiner

• 1 used when mentioning someone or something for the first time; the indefinite article.

  ■ one single: a hundred.

  ■ used when mentioning someone unfamiliar: a Mr Smith telephoned.

  ■ someone like (the name specified).

• 2 in, to, or for each; per: petrol prices rose by 3p a litre.

– origin ME: weak form of OE ān ‘one’.

usage: On the question of using a or an before words beginning with h, see usage at an.

Concise Oxford English Dictionary © 2008 Oxford University Press:
a2

▶abbreviation

• 1 (in travel timetables) arrives.

• 2 atto- (10⁻¹⁸).

• 3 Brit. (with reference to sporting fixtures) away.

• 4 (used before a date) before. [from L. ante.]

▶symbol (a) Physics acceleration.

Concise Oxford English Dictionary © 2008 Oxford University Press:
-a1

▶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: stanza.

– origin representing a Gk, L., or Romance fem. sing.

Concise Oxford English Dictionary © 2008 Oxford University Press:
-a2

▶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: Insectivora.

Concise Oxford English Dictionary © 2008 Oxford University Press:
-a3

▶suffix informal

• 1 of: coupla.

• 2 have: mighta.

• 3 to: oughta.

Concise Oxford English Dictionary © 2008 Oxford University Press:
a-1 (often an- before a vowel)

▶prefix not; without: atheistic.

– origin from Gk.

Concise Oxford English Dictionary © 2008 Oxford University Press:
a-2

▶prefix

• 1 to; towards: aside.

• 2 in the process of: a-hunting.

  ■ in a specified state: aflutter.

– origin OE, unstressed form of on.

Concise Oxford English Dictionary © 2008 Oxford University Press:
a-3

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

Concise Oxford English Dictionary © 2008 Oxford University Press:
a-4

▶prefix

• 1 of: anew.

• 2 utterly: abash.

– origin unstressed form of of (sense 1); Anglo-Norman Fr. a-, from L. ex (sense 2).

Concise Oxford English Dictionary © 2008 Oxford University Press:
ad- /ad/ (also a- before sc, sp, st; ac- before c, k, q; af- before f; ag- before g; al- before l; an- before n; ap- before p; ar- before r; as- before s; at- before t)

▶prefix

• 1 denoting motion or direction to: advance.

• 2 denoting reduction or change into: adulterate.

• 3 denoting addition or increase: adjunct.

– origin from L. ad ‘to’.

Concise Oxford English Dictionary © 2008 Oxford University Press:
ampere /ˈampɛː/ (abbrev.: A)

▶noun the SI base unit of electric current, equal to a flow of one coulomb per second.

– origin C19: named after the French physicist André-Marie Ampère.

Concise Oxford English Dictionary © 2008 Oxford University Press:
angstrom /ˈaŋstrəm/ (also ångström /ˈɒŋstrəːm/) (abbrev.: Å)

▶noun Physics a unit of length equal to one hundred millionth of a centimetre, 10⁻¹⁰ metre.

– origin C19: named after the Swedish physicist A. J. Ångström.