epsilon

Etymology

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

noun

1. The name for the fifth letter of the Greek alphabet, ε or Ε, preceded by delta (Δ, δ) and followed by zeta (Ζ, ζ).
2. (phonetics) In IPA, the phonetic symbol ɛ that represents the open-mid front unrounded vowel.
3. (mathematics) An arbitrarily small quantity.
   1. (colloquial) A small child.
4. (computing, colloquial) Something negligible or insignificant.
   All right, okay. My interest is epsilon. 2017, Dean Koontz, The Silent Corner, page 106
   Yes, we have to convert all the symbol names to upper case at startup, but that’s epsilon.
5. (finance) The percentage change in an option value with respect to the underlying dividend yield.