- not any particular or certain one of a class or group: a man; a chemical; a house.
- a certain; a particular: one at a time; two of a kind; A Miss Johnson called.
- another; one typically resembling: a Cicero in eloquence; a Jonah.
- one (used before plural nouns that are preceded by a quantifier singular in form): a hundred men (compare hundreds of men); a dozen times (compare dozens of times).
- indefinitely or nonspecifically (used with adjectives expressing number): a great many years; a few stars.
- one (used before a noun expressing quantity): a yard of ribbon; a score of times.
- any; a single: not a one.
- each; every; per: ten cents a sheet; three times a day.
- a reduced, unstressed form of of (often written as part of a single, unhyphenated word): cloth a gold; time a day; kinda; sorta.
- 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.
- are; ares.
- all: for a' that.
- 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.
- from beginning to end; thoroughly; completely: He knows the Bible from A to Z.
- to know nothing; be ignorant.
- ampere; amperes.
- angstrom; angstroms.
- answer.
- arterial (used with a road number to designate a major highway): Take the A525 to Ruthin.
- the first in order or in a series.
- Sometimes a .
- (in some grading systems) a grade or mark, as in school or college, indicating the quality of a student's work as excellent or superior.
- (in some school systems) a symbol designating the first semester of a school year.
- Music.
- the sixth tone in the scale of C major or the first tone in the relative minor scale, A minor.
- a string, key, or pipe tuned to this tone.
- a written or printed note representing this tone.
- (in the fixed system of solmization) the sixth tone of the scale of C major, called la.
- the tonality having A as the tonic note.
- a major blood group, usually enabling a person whose blood is of this type to donate blood to persons of group A or AB and to receive blood from persons of O or A.
- the medieval Roman numeral for 50 or 500.
- (formerly) argon.
- mass number.
- Biochemistry.
- universal affirmative.
- a designation for a motion picture recommended as suitable for adults.
- a proportional shoe width size, narrower than B and wider than AA.
- a proportional brassiere cup size, smaller than B and larger than AA.
- a quality rating for a corporate or municipal bond, lower than AA and higher than BBB.
- 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).
- a reduced form of the Old English preposition of: akin; afresh; anew.
- 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).
- variant of ab- before p and v: aperient; avert.
- 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.
- variant of an-1 before a consonant, meaning “not,” “without”: amoral; atonal; achromatic.
- atomic (used in combination): A-bomb; A-plant.
- a plural ending of nouns borrowed from Greek and Latin: phenomena; criteria; data; errata; genera.
- a feminine singular ending of nouns borrowed from Latin and Greek, also used in New Latin coinages to Latinize bases of any origin, and as a Latin substitute for the feminine ending -ē of Greek words: anabaena;cinchona;pachysandra.
- an ending of personal names forming feminines from masculines: Georgia; Roberta.
- a suffix designating the oxide of the chemical element denoted by the stem: alumina; ceria; thoria.
- angstrom.
- year.
- before.
- about.
- acre; acres.
- active.
- adjective.
- alto.
- ampere; amperes.
- anonymous.
- answer.
- are; ares.
- assist; assists.
- year.
- before.
- Absolute.
- Academy.
- acre; acres.
- America.
- American.
- angstrom.
- answer.
- April.
- Artillery.
- used preceding a singular countable noun, if the noun is not previously specified or known
- used preceding a proper noun to indicate that a person or thing has some of the qualities of the one named
- used preceding a noun or determiner of quantity
- used preceding a noun indicating a concrete or abstract thing capable of being divided
- each or every; per
- a certain; one
- any at all
- an informal or dialect word for have they'd a said if they'd known
- (usually linked to the preceding noun) an informal form of of sorta sad; a kinda waste
- acceleration
- are(s) (metric measure of land)
- atto-
- chess See algebraic notation
- 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
- the first in a series, esp the highest grade or mark, as in an examination
- from start to finish, thoroughly and in detail
- Scot variants of all
- music
- a note having a frequency of 440 hertz (A above middle C) or this value multiplied or divided by any power of 2; the sixth note of the scale of C major
- a key, string, or pipe producing this note
- the major or minor key having this note as its tonic
- a human blood type of the ABO group, containing the A antigen
- (in Britain) a major arterial road
- (formerly, in Britain)
- a film certified for viewing by anyone, but which contains material that some parents may not wish their children to see
- (as modifier)
- mass number
- the number 10 in hexadecimal notation
- ace
- argon (now superseded by Ar)
- ampere(s)
- ampere-turn
- absolute (temperature)
- (in circuit diagrams) ammeter
- area
- atomic
- affinity
- adenine
- a universal affirmative categorical proposition, such as all men are mortal: often symbolized as SaP
- a person whose job is in top management, or who holds a senior administrative or professional position
- (as modifier)
- Austria (international car registration)
- not; without; opposite to
- on; in; towards
- in the act or process of
- in the condition or state of
- angstrom unit
- acre(s) or acreage
- America(n)
- answer