Delta

If you asked Eric Clapton, Joe Bonamassa, Keith Richards, or any other rock star whose music is based on the blues, he'll tell you the Delta is the place in Mississippi where Robert Johnson made a deal with the Devil at the crossroads to sell his soul in order to become King of the Blues.

If you ask an options trader, she'll explain that delta is the premium result of the ratio between the option derivative vs. the underlying asset. Call and put options will usually have mirror image delta ratios relative to a strike price, so if the delta for an option series is 0.41, the price of the option will rise or fall +/- 0.41 for each dollar above or below the strike price. Other factors that can affect delta are open interest (liquidity), time value, and historical volatility.

Think: delta = change. As in: your mother telling you to delta your sheets.