pre ‧ ven ‧ tion /prɪˈvenʃ ə n/ BrE AmE noun [uncountable]
[ Word Family: adjective : ↑ preventable , PREVENTIVE/PREVENTATIVE ; verb : ↑ prevent ; noun : ↑ prevention ; adverb : PREVENTIVELY/PREVENTATIVELY ]
when something bad is stopped from happening
prevention of
Educating new drivers is important for the prevention of accidents.
crime/accident/fire etc prevention
Effective crime prevention must be our main goal.
a fire prevention officer
You know what they say, prevention is better than cure (=it is better to stop something bad from happening than to remove the problem once it has happened) .