Maintenance done to keep something in working order rather than to repair damage that has already happened.

(US) Prevention of a loss of profit (instances of theft, fraud, etc.) done by retail stores. / (US) The department or a person who is employed to carry out loss prevention.

Work done by the coastguard to prevent smuggling.

plural of preventive service

(medicine) medicine given to prevent illness, rather than treat it.

(team sports) Any defense intended to prevent rapid scoring by the offense, at the expense of allowing relatively easy, slower scoring.

plural of preventive war

plural of loss prevention

plural of blowout preventer

It is better to prevent the creation of a problem than to have to deal with it afterwards.