Someone who guards, watches over, or protects.
"The old oak tree served as a guardian for the small garden, shielding it from strong winds and heavy rains."
In plain English: A guardian is an adult who takes care of someone else, usually a child or elderly person, when their parents cannot do it themselves.
"The dog acted as a loyal guardian for the small children in the park."
Usage: A guardian is a person legally appointed to care for a minor or an incapacitated adult, protecting their well-being and managing their affairs. While anyone can watch over something, the term specifically implies a formal responsibility for another person's safety and welfare.
A British daily national newspaper.
"The Guardian reported on the latest developments in the local council meeting yesterday."
The word guardian comes from the Middle English gardein and Old French guardein, which both derive from a Germanic root meaning to protect or watch over. Although it looks like a combination of "guard" and "-ian," its history traces back directly to these earlier forms rather than being formed recently in English.