Definition:Weakly Abnormal Subgroup/Definition 3

Definition
Let $G$ be a group.

Let $H$ be a subgroup of $G$.

$H$ is weakly abnormal in $G$ :
 * if $H \le K \le G$, then $K$ is a contranormal subgroup of $G$

where $H \le K$ denotes that $H$ is a subgroup of $K$.

Also see

 * Equivalence of Definitions of Weakly Abnormal Subgroup