1. to move quickly away from someone or something If a big truck bears down on you from behind, this powerful car can leave it in the dust. 2. to replace someone or something with something new This new computer virus left last year's killer virus in the dust.
1. to move quickly away from someone or something If a big truck bears down on you from behind, this powerful car can leave it in the dust. 2. to replace someone or something with something new This new computer virus left last year's killer virus in the dust.
I believe it comes from the experience of having someone pass you so rapidly that you are running (or riding, in the case of a car) in the dust they have kicked up. Having grown up along dusty country roads I have had several experiences of this.