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early 14c., from Old French oficial "law officer; bishop's representative" (12c.) and directly from Late Latin officialis "attendant to a magistrate, public official," noun use of officialis (adj.) "of or belonging to duty, service, or office" (see official (adj.)). Meaning "person in charge of some public work or duty" first recorded 1550s.
late 14c., "performing a service; required by duty," from Old French oficial "official; main, principal" (14c., Modern French officiel) or directly from Late Latin officialis "of or belonging to duty, service, or office," from Latin officium (see office). Meaning "pertaining to an office or official position" is from c.1600.
official of·fi·cial (ə-fĭsh'əl)
Authorized by or contained in the U.S. Pharmacopoeia or National Formulary. Used of drugs.