noun

• (international standards) Alternative letter-case form of Delta from the NATO/ICAO Phonetic Alphabet.
• (mathematics, physics, engineering) The symbol Δ; A change in a quantity, likely from "d" for "difference".
  "ΔV - "delta vee"(change in velocity, used in rocketry and orbital mechanics)"
• (finance) The rate of change in an option value with respect to the underlying asset's price.
• (chemistry) A value in delta notation indicating the relative abundances of isotopes.

verb

• (cryptography) To calculate the differences between the characters in an enciphered text and the characters a fixed number of positions previous.
  "Turingery worked on deltaed key to produce the deltaed contribution of the chi-wheels. Turing's discovery that delta-ing would reveal information otherwise hidden was essential to the developments that followed."
• (computing) To compare two versions of the same file in order to determine where they differ (where a programmer has made edits).
  "The primary function of this command is to delta the product version file (if it has been retrieved for edit). However, prior to deltaing the product version file, the work source tree is searched to verify that no other source files are still waiting to be deltaed."