Crux and Toughie

Crux noun - The central part or aspect of something under consideration.

Toughie and crux are semantically related. In some cases you can use "Toughie" instead a noun "Crux".

Toughie noun - A violent, brutal person who is often a member of an organized gang.

Crux and toughie are semantically related. Sometimes you can use "Crux" instead a noun "Toughie".