Some cards have text describing special powers that the item or zombie possess. These powers are referred to as abilities. Each ability does something different, but many are related to how zombies interact with each other in combat.
Some abilities appear frequently enough between zombies that their text has been shortened to a single keyword to save space. At the bottom of this page is a catalog of all the keywords which are used as shorthand to describe common abilities.
Most keyword abilities are active at all times, but many abilities that are described without keywords (and some keyword abilities) only activate when a specific Trigger condition is met.