Vermeiden
The most universal word in German for “to avoid”, in the sense of not letting something happen or to get out of the way of something, is vermeiden (or, to a lesser degree, meiden). The noun for “avoidance” or “prevention” is Vermeidung (f.).
Bonus Words
If you want to express the situation in the sense of “to dodge” or “to evade”, the German word is ausweichen. Another useful word that literally means “to go around” or “to circumvent” is umgehen.
Examples
Wir müssen vermeiden, dass etwas schlimmes passiert. We have to avoid something bad from happening.
Ich will Verwirrung vermeiden. I want to avoid confusion.
Genau das wollte ich vermeiden. That’s exactly what I wanted to prevent.
Wir tragen zur Vermeidung von Umweltverschmutzung bei. We’re contributing toward the avoidance of environmental pollution.
Wenn er den Schraubenschlüssel wirft musst du ihm ausweichen. When he throws the wrench you need to dodge it.
Wir müssen die Baustelle umgehen. We have to walk around the constuction site.