angstrom, angstrom unit, A (noun)

a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation

vitamin A, antiophthalmic factor, axerophthol, A (noun)

any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes

deoxyadenosine monophosphate, A (noun)

one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)

adenine, A (noun)

(biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA

ampere, amp, A (noun)

the basic unit of electric current adopted under the Systeme International d'Unites

"a typical household circuit carries 15 to 50 amps"

A, a (noun)

the 1st letter of the Roman alphabet

A, type A, group A (noun)

the blood group whose red cells carry the A antigen

a (Pronoun)

Alternate form of a.

A (Noun)

An academic grade issued by certain educational institutions. Slightly better than an A.

A (Noun)

The highest possible rating.

A (Noun)

An academic grade. Where it is used, it is often the best class of result.

A (Noun)

A best-first graph search algorithm for finding a lowest cost path to a goal.

a (Adverb)

Alternate spelling of a

a (Adjective)

Alternate spelling of a

A

A is the first letter and vowel in the ISO basic Latin alphabet. It is similar to the Ancient Greek letter alpha, from which it derives.

A

A (named, plural As, A's, as, a's or aes) is the first letter and the first vowel of the modern English alphabet and the ISO basic Latin alphabet. It is similar to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version can be written in two forms: the double-storey a and single-storey ɑ. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English grammar, "a", and its variant "an", is an indefinite article.