A

   1. a symbol for international standard paper sizes, followed by the size number, as in A4 for a standard business-letter sheet. A table of sizes is provided. A sheet of size A<VAR>n</VAR> has a width of 100·2^-1/4-<VAR>ⁿ</VAR>^/2centimeters and a length of 100·2^1/4-<VAR>ⁿ</VAR>^/2 centimeters (rounded to the nearest millimeter). Note: "A" is also the SI symbol for the ampere (see below).

   2. shortened version of am or AM in a statement of time (see below).

   3. see acre

   4. see angstrom