C

   1. the Roman numeral 100, sometimes used as a unit of quantity or as a prefix meaning 100, as in Cwt (hundredweight) or CCF (100 cubic feet).

   2. a symbol for international standard paper sizes, followed by the size number, as in C4. The C series of sizes is used primarily for envelopes. A table of sizes is provided.

   3. a unit of relative current for batteries. For a particular battery, a current of 1C is a current in amperes numerically equal to the rated capacity of the battery in ampere hours. In other words, a 1C current will completely charge or discharge the battery in one hour.

   4. see coulomb