Perfect field

Definition
A field is said to be perfect if one of the following conditions holds:


 * The field has characteristic zero
 * The field has characteristic $$p$$ and the map $$x \mapsto x^p$$ is surjective (and hence, bijective, and hence, a field isomorphism)

Stronger properties

 * Finite field
 * Algebraically closed field
 * Field of characteristic zero