Zombies tend to flock together since their limited instincts tell them that greater numbers means easier human kills. Those of us in the professional paranormal community always refer to an accumulation of zombies within an area of up to several acres as a horde of zombies. The term horde is used the most among zombie hunters, and Cryptozoologists. If just a small area has a group of zombies, such as a building, or small graveyard, it’s called an infestation of zombies. A more widespread lot consisting of nearly an entire community or more are called a plague of zombies. A large area of a nation infested with zombies is called a zombie epidemic. An entire country or continent of zombies would be called a zombie pandemic.
If the whole Earth were plagued by zombies then it would be referred to as a Zombie Apocalypse. In the distant future if a zombie pandemic spread to other planets, and star systems it would be called a Zombie Hyper-Apocalypse. In general supernatural investigators will refer to zombies as the zombie scourge, or a potential zombie virus outbreak as the zombie menace. However you will most likely only deal with one lone zombie in your lifetime, and even then you won’t realize what you’re dealing with. Consider yourself lucky! Now you know the proper terms should you encounter zombies which is of course the first thing you’re thinking of. The whole being eaten alive thing is just a second thought. 🙂