epsilon

noun

Etymology: From Ancient Greek ἒ ψιλόν (è psilón, “simple Ε”).

1. The fifth letter of the Greek alphabet, ε or Ε, preceded by delta (Δ, δ) and followed by zeta (Ζ, ζ).
2. In IPA, the phonetic symbol ɛ that represents the open-mid front unrounded vowel.
3. An arbitrarily small quantity.
4. An arbitrarily small quantity.
5. Something negligible or insignificant.

   “Yes, we have to convert all the symbol names to upper case at startup, but that’s epsilon.”

   “All right, okay. My interest is epsilon.”

6. The percentage change in an option value with respect to the underlying dividend yield.