Mathematics: very small, Levi Zivita symbol.
Physics: dielectric constant, energy quantum.
Lower case ε is used for:
Math:
Very small
The ∈ symbol indicating "belonging" in a set relation.
Levi-Civita symbol (levi-Civita symbol)
Computer science:
blank line
Accuracy of number types
Physics: Dielectric Constant of Conductor
The phonetic symbol used in American English is the e sound of bed.
The Latin letter e is changed from Epsilon.