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.
a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation
the basic unit of electric current adopted under the Systeme International d'Unites
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.
any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
An adjective, commonly called the indefinite article, and signifying one or any, but less emphatically.
one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)
In each; to or for each; as, "twenty leagues a day", "a hundred pounds a year", "a dollar a yard", etc.
In; on; at; by.
(biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
the blood group whose red cells carry the A antigen
In process of; in the act of; into; to;
the 1st letter of the Roman alphabet
A barbarous corruption of have, of he, and sometimes of it and of they.
An expletive, void of sense, to fill up the meter
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-.
Not, without, -less; equivalent to l. in- and e. un-.