Science Fair Project Encyclopedia
The letter A is the first letter in the Latin alphabet.
When the Ancient Greeks adopted the alphabet, they had no use for the glottal stop that the letter had denoted in Phoenician and other Semitic languages, so they used the sign for the vowel , and changed its name to alpha. In the earliest Greek inscriptions, dating to the 8th century BC, the letter rests upon its side, but in the Greek alphabet of later times it generally resembles the modern capital letter, although many local varieties can be distinguished by the shortening of one leg, or by the angle at which the cross line is set.
The Etruscans brought the Greek alphabet to what was Italy and left the letter unchanged. The Romans later adopted the Etruscan alphabet to write Latin, and the resulting letter was preserved in the modern Latin alphabet used to write many languages, including English.
The modern lowercase letter a derives from Greek handwriting, which evolved from a form similar to the current capital to a circular shape with a projection by the 4th century.
Modern Roman A
Modern Italic A
Modern Script A
In English, the letter A by itself usually denotes the lax open front unrounded vowel (IPA /æ/) as in pad, the open back unrounded vowel (IPA /ɑ/) as in father, or, in concert with a later e, the diphthong /eɪ/ (though the actual pronunciation depends on the dialect) as in ace, due to effects of the Great vowel shift.
In the International Phonetic Alphabet, variants of the letter A denote various vowels. In X-SAMPA, capital A denotes the open back unrounded vowel and lowercase a denotes the open front unrounded vowel.
In the NATO phonetic alphabet the letter A is Alfa (which may also be spelled Alpha in English-only environments).
In international Morse code the letter A is DitDah: · -
X. .. ..
The EBCDIC code for capital A is 193 and for lowercase a is 129.
Meanings for A
- In baseball, the Oakland Athletics are often simply referred to as the "A's".
- In biochemistry, A is the symbol for alanine and adenosine.
- In calendars, A is often an abbreviation for the months April and August.
- In computing,
- In education, a grade of A typically represents the highest score that students can achieve. (sometimes coupled with a plus/minus sign - i.e., A+ or A-, or a number - e.g., A1)
- In electronics,
- In film, A is an Italian film made in 1969; see A (film) .
- In financial securities, A is the stock symbol for Agilent Technologies.
- In English, the word "a" is an indefinite article, see A, an
- In Greek, a- is a prefix (alpha privativum) meaning "not" or "devoid of", used in many borrowed words in English, German and Romance languages.
- In international licence plate codes, A stands for Austria.
- In international paper sizes, A is a series of sizes with an aspect ratio of roughly 70% width to height, with A4 being an example popular size.
- In logic,
- the letter A is used as a symbol for the universal affirmative proposition in the general form "all x is y". The letters I, E and O are used respectively for the particular affirmative "some x is y", the universal negative "no x is y", and the particular negative "some x is not y". The use of these letters is generally derived from the vowels of the two Latin verbs affirmo (or AIo), "I assert", and nego, "I deny". The use of the symbols dates from the 13th century, though some authorities trace their origin to the Greek logicians.
- In symbolic logic, the symbol ∀ (an inverted letter A) is the universal quantifier.
- In mathematics,
- In medicine, A is one of the human blood types.
- In the Metric system,
- In music,
- In a deck of playing cards, the letter A is used to mark each of the Aces.
- In political theory, a circumscribed "A" is an anarchist symbol.
- As the first letter of a postal code,
- As a timezone, A is the military designation for Coordinated Universal Time+1, also known as CET or Central European Time.
- In photography, most SLR cameras use A to signify aperture priority mode, where the user sets the aperture and the camera determines the shutter speed.
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