division sign

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The symbol (÷) placed between two quantities written on a single line to indicate the division of the first by the second.
• noun The symbol (/) placed between two quantities written horizontally, as in ²/₃ , or the symbol (–) placed between two quantities written vertically, as in ²/₃ , to indicate a fraction.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics Any symbol (in particular ÷ or / ) used to denote the operation of division.