crowded with or characterized by much activity; "a very busy week"; "a busy life"; "a busy street"; "a busy seaport"
actively or fully engaged or occupied; "busy with her work"; "a busy man"; "too busy to eat lunch"; "the line is busy"
(of facilities such as telephones or lavatories) unavailable for use by anyone else or indicating unavailability; (`engaged' is a British term for a busy telephone line); "her line is busy"; "receptionists' telephones are always engaged"; "the lavatory is in use"; "kept getting a busy signal"
overcrowded or cluttered with detail; "a busy painting"; "a fussy design"
keep busy with; "She busies herself with her butterfly collection"
requiring effort or concentration; complex and not easy to answer or solve; "raised serious objections to the proposal"; "the plan has a serious flaw"
of great consequence; "marriage is a serious matter"
concerned with work or important matters rather than play or trivialities; "a serious student of history"; "a serious attempt to learn to ski"; "gave me a serious look"; "a serious young man"; "are you serious or joking?"; "Don't be so serious!"
(pharmacology) a book containing a compilation of pharmaceutical products with their formulas and methods of preparation; "postexposure prophylaxis is an integral part of the pharmacopeia in preventing severe disease after acute infections"