cus ‧ to ‧ di ‧ an /kʌˈstəʊdiən $ -ˈstoʊ-/ BrE AmE noun [countable]
1 . someone who is responsible for looking after something important or valuable
custodian of
Farmers are custodians of the land for the next generation.
2 . especially American English someone who looks after a public building:
a custodian at the stadium
3 . custodian of tradition/moral values etc someone who tries to protect a traditional set of beliefs, attitudes etc