1. Following, pursuing, or tracking someone or something. Police are on the track of two armed men who held up a liquor store late last night. Our top detective is on the track of the stolen goods, sir.

2. On course to do something; heading toward some action as expected, planned, or desired. My family assumed I was still on the track of becoming a doctor, as I hadn't told them that I'd dropped out. I believe our team is on the track of revolutionizing the treatment of cancer.