difficult to accomplish; demanding considerable mental effort and skill; "the arduous work of preparing a dictionary"
characterized by toilsome effort to the point of exhaustion; especially physical effort; "worked their arduous way up the mining valley"; "a grueling campaign"; "hard labor"; "heavy work"; "heavy going"; "spent many laborious hours on the project"; "set a punishing pace"
taxing to the utmost; testing powers of endurance; "his final, straining burst of speed"; "a strenuous task"; "your willingness after these six arduous days to remain here"- F.D.Roosevelt
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"