Custodian/kʌˈstəʊdiən/ Definition 1 of 3Pro Tip 1/3Care Responsibility Indicates ongoing responsibility for care, often used for buildings or institutions. As a museum custodian, she protects the art. Pro Tip 2/3Not Ownership Being a custodian doesn't mean you own what you're looking after. He is the custodian of the lost phone. Pro Tip 3/3Protector Role The word implies a protective, caring role beyond just cleaning and maintenance. School custodians ensure a safe environment for students.