Virus is a microscopic organism that lives in a cell of another living thing. Although viruses are extremely small and simple, they are a major cause of disease. Some viruses infect human beings with such diseases as measles, influenza, and the common cold.
Passive Mobs. Passive mobs are composed of creatures that will never, under any circumstances, attack the player. Some passive mobs can be bred to create more of them, e.g. pigs can be bred to effectively farm them.
A mob, mobile or monster is a computer-controlled non-player character (NPC) in a computer game such as an MMORPG or MUD. Depending on context, every and any such characters in a game may be considered to be a mob, or usage of the term may be limited to hostile NPCs and/or NPCs vulnerable to attack. Common usage refers to either a single character or a multitude of characters in a group as a mob. In most modern graphical games, mob may be used to specifically refer to generic monstrous NPCs that the player is expected to hunt and kill, excluding NPCs that engage in dialog or sell items or who cannot be attacked.