Of or relating to an office or a post of authority: official duties. Authorized by a proper authority; authoritative: official permission. Holding office or serving in a public capacity: an official representative. Characteristic of or befitting a person of authority; formal: an official banquet. Authorized by or contained in the U.S. Pharmacopoeia or National Formulary. Used of drugs. One who holds an office or position, especially one who acts in a subordinate capacity for an institution such as a corporation or governmental agency. Sports A referee or umpire.