1) Event in track cycling 
track meet with a variety of races.
An omnium (from Latin: of all, belonging to all) is a multiple race event in track cycling. Historically the omnium has had a variety of formats. In recent years, road racing has adopted the term to describe multi-day races that feature the three primary road race events. ==History== The omnium was re-introduced into the World Championships as a f...
• (n.) The aggregate value of the different stocks in which a loan to government is now usually funded.
See whatnot.
Om'ni·um noun [ Latin , of all, gen. plural of omnis all.] (Eng.Stock Exchange) The aggregate value of the different stocks in which a loan to government is now usually funded. M'Culloch. 
A track racing event in which riders compete against each other in five different disciplines including the 200-meter flying-start time trial, the 5-kilometer scratch race, the 3-kilometer individual pursuit, the 15-kilometer points race and the 1-kilometer time trial.
A stage race or series of races scored on points rather than overall time. Unlike a stage race, omniums often allow riders to pick and choose the races they want to enter.