Definition 1
The difference between the current Bid and the current Ask (in Over-the-Counter trading) or offered (in Exchange trading) of a given security;
also called Bid/ask spread.
Definition 2
The Purchase of one Option and the simultaneous sale of a related option, such as two options of the same Class but different strike prices and/or Expiration date. also called Spread option.
Definition 3
More generally, the difference between any two prices.
