TITLE: Is there a name for "co-normal" subgroups?
QUESTION [5 upvotes]: I have in mind a situation where a group $G$ has two subgroups $H$ and $K$ with the property that each of them is closed under conjugation by elements of the other.
More formally: for $h \in H$ and $k \in K$ then $h^{-1} k h \in K$ and $k^{-1}h k \in H$.
Is there a name for this?

REPLY [2 votes]: By far the most popular according to Google is "$H$ and $K$ normalize each other".