Greek Small Letter Epsilon

U+03B5

\epsilon

The (epsilon) symbol is used in math as a variable to represent error bounds. For example, in calculus, limits are formally defined using the (epsilon-delta) definition^[1].

Greek Small Letter Delta | Symbol

The Greek small letter delta (δ) is used in math as a variable. It appears in calculus in epsilon-delta notation.

Greek Capital Letter Epsilon | Symbol

The capital Greek letter (Ε).

1. (ε, δ) "epsilon delta" definitions of limits
   Grant Sanderson (3Blue1Brown)
   https://3blue1brown.com/lessons/epsilon-delta