"safe enclosure" refers to a protected or secure space where someone feels safe and out of harm's way. It can be a physical place like a well-protected building or a mental state where one feels emotionally secure. Full definition
There are also lots of safe enclosures for cats to spend supervised outdoor time in. (mypawsitivelypets.com)
These activities are conducted with safety in mind, and the rodents are kept in safe enclosures, so that the dogs can't actually get to them. (petwave.com)
Rabbits do not require outdoor exercise; if allowed outdoors, your rabbit must be in a predator - safe enclosure covered on all sides, and in the shade. (laanimalservices.com)