Custodian

google

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late 18th century: from custody, on the pattern of guardian .

wiktionary

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From Medieval Latin *custōdiānus(“the office of a custōdia”), implied in custōdiānātus, from Latin custōdia(“a keeping, watch, guard, prison”), from custōs(“a keeper, watchman, guard”).

etymonline

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custodian (n.)

1781, "one who has the care or custody of anything" (a library, a lunatic, etc.), from custody (Latin custodia) + -an. In this sense Middle English had custode (late 14c.), custodier (late 15c.). As "janitor," by 1944, American English, short for custodian-janitor (by 1899). Related: Custodianship.