/ ˈgɑːdiən; NAmE ˈgɑːrd-/ noun
1.
a person who protects sth
SYN custodian :
Farmers should be guardians of the countryside.
The police are guardians of law and order.
2.
a person who is legally responsible for the care of another person, especially a child whose parents have died
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WORD ORIGIN
late Middle English : from Old French garden , of Germanic origin; compare with ward and warden . The ending was altered by association with -ian .