epsilon

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. In IPA, the phonetic symbol ɛ that represents the open-mid front unrounded vowel.
3. An arbitrarily small quantity.
4. A negligible effect.“Yes, we have to convert all the symbol names to upper case at startup, but that’s epsilon.”