Definition for A

1. (physics) The symbol for ampere, a unit of electricalRelated to electricity (or electronics) current in the InternationalOf or having to do with more than one nation System of Units.
2. (biochemistry) The symbol for the nucleosidean organic molecule in which a nitrogenous heterocyclic base (or nucleobase), which can be either a double-ringed purine or a single-ringed pyrimidine, is covalently attached to a five-carbon pentose sugar (deoxyribose in DNA or ribose in RNA). When the phosphate group is covalently attached to the pentose sugar, it forms a nucleotide. adenosine, a nucleoside derived from adenine and ribose or the nucleobasethe base of a nucleic acid in either RNA or DNA. These bases include cytosine, guanine, adenine, thymine (in DNA) and uracil (in RNA). They are abbreviated as C, G, A, T, and U, respectively. Nucleobases may pair non-cavalently (or hydrogen bond) with a complementary base of another nucleic acid in a process called "base pairing"). adenine containedRestricted in space. in DNA.
3. (biochemistry) The one-letter symbol for alanine, one of the natural amino acids.
4. (computing) hexadecimal(arithmetic, computing) A number system with base 16, using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F, useful in computing as numbers in hexadecimal can be stored in four bits. Informal short form used in computing: hex symbol for 10