A, a, the first letter in the English alphabet, as in those of all the modern Indo-European tongues. The Latin alphabet also commences with a, and the Greek with a similar letter, alpha. In Sanscrit the vowels are classified by grammarians separately from the consonants. The vowels are placed first, and two sounds of a, the first a very short one, intermediate between ? and ?, as in the word Veda, and the other long, as in the first syllable of Brahman, head the list. In the Semitic, also, more accurately called the Syro-Arabian, family of languages, a letter with the a sound stands first in order. Thus the Hebrew alphabet commences with A (Aleph), followed in succession by B (Beth), C (Gimel), D (Daleth), designations which at once suggest the names of the Greek letters Alpha, Beta, Gamma, Delta. The old Hebrew, the Aramæan, and the Greek letters seem to have come from the Phoenician, a Syro-Arabian tongue. The Phoenician letters, again, as Gesenius suggests, may have been derived from the Egyptian hieroglyphics.
A as an initial is used:
- In chronology, for Anno (Lat.)=in the year, as A. D., Anno Domini=in the year of our Lord; A. U. C., Anno urbis conditæ=in the year of the city founded--i. e., from the foundation of the city (Rome)=753 B. C. (Varro).
- In horology, for the Lat. prep. ante=before, as a. m. (ante meridiem)=before noon.
- In designating university degrees, for Artium, as A. M. (Lat.), or M. A. (Eng.), Artium Magister=Master of Arts; A. B. (Lat.), or B. A. (Eng.), Artium Baccalaureus=Bachelor of Arts.
- In music, for alto, as S. A. T. B.=soprano, alto, tenor, bass.
- In nautical language, for able. Thus, A. B.=able-bodied seaman.
- In commerce, for accepted, and is used specially of bills.
A as a symbol stands for:
- In logic, a universal affirmative.
- In music, the 6th note of the diatonic scale of C major corresponding to the la of the Italians and the French.
- In heraldry, the chief in an escutcheon.
- In nautical language, A-1=a vessel of the first class, excellently built. Figuratively, anything highly excellent; the best of its class.
- In mathematics, A and the other letters of the alphabet are used, e. g., in Euclid, to represent lines, angles, points, etc. In algebra, a and the other first letters of the alphabet are used to express known quantities, and the last letter to express such as are unknown.