Epsilon zero
= Epsilon zero
{title2=$\varepsilon_0$}
= Least fixed point of omega exponentiation
{synonym}
The <ordinal> $\varepsilon_0$ is the least fixed point of $\alpha\mapsto\omega^\alpha$. It is the supremum of $1,\omega,\omega^\omega,\omega^{\omega^\omega},\ldots$, and is countable.