definition for VIX?

Answer 1

"The VIX Index is an implied volatility
index that measures the market’s expectation of 30-day
S&P 500® volatility implicit in the prices of near-term S&P
500 options. VIX is quoted in percentage points, just like the
standard deviation of a rate of return."

For more information on VIX see

http://www.cboe.com/micro/vix/VIXoptionsQRG.pdf