Definition of deltas:
(n) :
A landform at the mouth of a river where it empties into a body of water.
(n) :
(mathematics, physics, engineering) The symbol Δ; A change in a quantity, likely from "d" for "difference".
(n) :
(finance) The rate of change in an option value with respect to the underlying asset's price.
(n) :
The fourth letter of the modern Greek alphabet Δ, δ.
(n) :
(computing) The set of differences between two versions of a file.
(n) :
(chemistry) A value in delta notation indicating the relative abundances of isotopes.