a
pronunciation
How to pronounce a in British English:
UK [ə]
How to pronounce a in American English:
US [ə]
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- Noun:
- the blood group whose red cells carry the A antigen
- a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
- any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
- one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)
- (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
- the basic unit of electric current adopted under the Systeme International d'Unites
- the 1st letter of the Roman alphabet
Word Origin
- a
- a: [OE] The indefinite article in English is ultimately identical with the word one (as is the case, even more obviously, in other European languages – French un, German ein, and so on). The ancestor of both a(n) and one was ān, with a long vowel, but in the Old English period it was chiefly used for the numeral; where we would use a(n), the Anglo-Saxons tended not to use an article at all. Ān begins to emerge as the indefinite article in the middle of the 12th century, and it was not long before, in that relatively unemphatic linguistic environment, its vowel became weakened and shortened, giving an.And at about the same time the distinction between an and a began to develop, although this was a slow process; until 1300 an was still often used before consonants, and right up to 1600 and beyond it was common before all words beginning with h, such as house.=> one
- a (1)
- indefinite article, mid-12c., a variation of Old English an (see an) in which the -n- began to disappear before consonants, a process mostly complete by mid-14c. The -n- also was retained before words beginning with a sounded -h- until c. 1600; it still is retained by many writers before unaccented syllables in h- or (e)u-, but is now no longer normally spoken as such. The -n- also lingered (especially in southern England dialect) before -w- and -y- through 15c.
- a (2)
- as in twice a day, etc., from Old English an "on," in this case "on each." The sense was extended from time to measure, price, place, etc. The habit of tacking a onto a gerund (as in a-hunting we will go) died out 18c.
Example
- 1. Turning the page here is like twisting a kaleidoscope .
- 2. Both groups had regular contact with a nutritional expert .
- 3. A layer mask can give individual pixels different opacities .
- 4. Almost all of us are suffering without a cause .
- 5. Up to a point the axiomatic approach worked .