man·tu·ary
1. An area of a (usually shared) residence where a male can enjoy his hobbies independent of normal house rules (usually of orderliness or cleanliness.) From "man" + "sanctuary".
2. A place where a man can go to get away from the world, more generally a place where your wife and your mistress are not. It can be a permanent structure such as a special room in the house (commonly a basement)or could be the fishing boat.
3. An area or activity that men congregate to let it all hang out with out being called disgusting. A place where men can freely scratch their balls, burp, fart and use foul language without having to worry about who they will offend.
4. A location where a man can be alone without certain distractions and gather his thoughts.

Example - After a 60 hour work week, Geoff decided to retreat to his mantuary. That way he would not have to listen to his wife Elisabeth b*t*h about the lawn.