- A tract of land shaped like the letter delta (/), especially
when the land is alluvial and inclosed between two or more mouths of a
river; as, the delta of the Ganges, of the Nile, or of the Mississippi.
Meaning of 'delta' (Princeton's WordNet)
1 . delta
[ n]
Meaning (1): - a low triangular area of alluvial deposits where a river divides before entering a larger body of water
Delta Delta is the change in an option’s price divided by the change in the price of the underlying instrument. Hedging strategies are based on delta ratios.