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Words starting with a

Word Definition
a 1. The first letter of the English and of many other alphabets. The capital A of the alphabets of Middle and Western Europe, as also the small letter (a), besides the forms in Italic, black letter, etc., are all descended from the old Latin A, which was borrowed from the Greek Alpha, of the same form; and this was made from the first letter (/) of the Phoenician alphabet, the equivalent of the Hebrew Aleph, and itself from the Egyptian origin. The Aleph was a consonant letter, with a guttural breath sound that was not an element of Greek articulation; and the Greeks took it to represent their vowel Alpha with the a sound, the Phoenician alphabet having no vowel symbols.
2. The name of the sixth tone in the model major scale (that in C), or the first tone of the minor scale, which is named after it the scale in A minor. The second string of the violin is tuned to the A in the treble staff. -- A sharp (A/) is the name of a musical tone intermediate between A and B. -- A flat (A/) is the name of a tone intermediate between A and G.
3. An adjective, commonly called the indefinite article, and signifying one or any, but less emphatically.
4. In each; to or for each; as, "twenty leagues a day", "a hundred pounds a year", "a dollar a yard", etc.
5. (prep.) In; on; at; by.
6. (prep.) In process of; in the act of; into; to; -- used with verbal substantives in -ing which begin with a consonant. This is a shortened form of the preposition an (which was used before the vowel sound); as in a hunting, a building, a begging.
7. (prep.) Of.
8. A barbarous corruption of have, of he, and sometimes of it and of they.
9. An expletive, void of sense, to fill up the meter
10. (n.) the blood group whose red cells carry the A antigen
11. (n.) the 1st letter of the Roman alphabet
12. (n.) the basic unit of electric current adopted under the Systeme International d'Unites
13. (n.) a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
14. (n.) (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
15. (n.) one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)
16. (n.) any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
a 1 1. A registry mark given by underwriters (as at Lloyd's) to ships in first-class condition. Inferior grades are indicated by A 2 and A 3.
A B C 1. The first three letters of the alphabet, used for the whole alphabet.
2. A primer for teaching the alphabet and first elements of reading.
3. The simplest rudiments of any subject; as, the A B C of finance.
A battery 1. (n.) the battery used to heat the filaments of a vacuum tube
a bit 1. (adv.) to a small degree; somewhat
a capella 1. (adj.) sung without instrumental accompaniment
2. (adv.) without musical accompaniment
a capella singing 1. (n.) singing without instrumental accompaniment
a cappella 1. In church or chapel style; -- said of compositions sung in the old church style, without instrumental accompaniment; as, a mass a capella, i. e., a mass purely vocal.
2. A time indication, equivalent to alla breve.
3. (adj.) sung without instrumental accompaniment
4. (adv.) without musical accompaniment
a cappella singing 1. (n.) singing without instrumental accompaniment
a couple of 1. (adj.) more than one but indefinitely small in number
a few 1. (adj.) more than one but indefinitely small in number
a fortiori 1. With stronger reason.
2. (adv.) with greater reason; for a still stronger, more certain reason
a good deal 1. (adv.) to a very great degree or extent
a great deal 1. (adv.) to a very great degree or extent
2. (adv.) frequently or in great quantities
A horizon 1. (n.) the top layer of a soil profile; usually contains humus
a hundred times 1. (adv.) by a factor of one hundred
a Kempis 1. (n.) German ecclesiastic (1380-1471)
a la carte 1. (adj.) (of a restaurant meal) having unlimited choices with a separate price for each item
2. (adv.) by ordering items listed individually on a menu
3. (n.) a menu having individual dishes listed with separate prices
a la mode 1. (adj.) in the current fashion or style
2. (adv.) with ice cream on top or on the side
A level 1. (n.) the advanced level of a subject taken in school (usually two years after O level)
a little 1. (adv.) to a small degree; somewhat
a lot 1. (adv.) to a very great degree or extent
a mensa et thoro 1. A kind of divorce which does not dissolve the marriage bond, but merely authorizes a separate life of the husband and wife.
a million times 1. (adv.) by a factor of a million
a posteriori 1. Characterizing that kind of reasoning which derives propositions from the observation of facts, or by generalizations from facts arrives at principles and definitions, or infers causes from effects. This is the reverse of a priori reasoning.
2. Applied to knowledge which is based upon or derived from facts through induction or experiment; inductive or empirical.
3. (adj.) involving reasoning from facts or particulars to general principles or from effects to causes
4. (adj.) requiring evidence for validation or support
5. (adv.) derived from observed facts
a priori 1. Characterizing that kind of reasoning which deduces consequences from definitions formed, or principles assumed, or which infers effects from causes previously known; deductive or deductively. The reverse of a posteriori.
2. Applied to knowledge and conceptions assumed, or presupposed, as prior to experience, in order to make experience rational or possible.
3. (adj.) involving deductive reasoning from a general principle to a necessary effect; not supported by fact
4. (adj.) based on hypothesis or theory rather than experiment
5. (adv.) derived by logic, without observed facts
a trifle 1. (adv.) to a small degree; somewhat
a- 1. A, as a prefix to English words, is derived from various sources. (1) It frequently signifies on or in (from an, a forms of AS. on), denoting a state, as in afoot, on foot, abed, amiss, asleep, aground, aloft, away (AS. onweg), and analogically, ablaze, atremble, etc. (2) AS. of off, from, as in adown (AS. ofd/ne off the dun or hill). (3) AS. a- (Goth. us-, ur-, Ger. er-), usually giving an intensive force, and sometimes the sense of away, on, back, as in arise, abide, ago. (4) Old English y- or i- (corrupted from the AS. inseparable particle ge-, cognate with OHG. ga-, gi-, Goth. ga-), which, as a prefix, made no essential addition to the meaning, as in aware. (5) French a (L. ad to), as in abase, achieve. (6) L. a, ab, abs, from, as in avert. (7) Greek insep. prefix / without, or privative, not, as in abyss, atheist; akin to E. un-.
A-bomb 1. (n.) a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239)
A-horizon 1. (n.) the top layer of a soil profile; usually contains humus