Librarian

google

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late 17th century (denoting a scribe or copyist): from Latin librarius ‘relating to books’, (used as a noun) ‘bookseller, scribe’, + -an.

wiktionary

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library +‎  -an. First attested around 1710. 

etymonline

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librarian (n.)

"custodian of a library," 1713; see library + -an. Earlier form was library-keeper (1640s), and librarian had been used in the sense "scribe, one who copies books" (1660s).