In baseball, a player who often hits home runs, running the full circuit of bases when they do so. The new circuit slugger has been an incredible asset to the team this season.

dated The itinerary of or route taken by a travelling evangelist preacher. (Variant of the more common "sawdust trail.") Primarily heard in US. Old Bill Baxton? Shoot, he's been on the sawdust circuit for the better part of his life. He probably wouldn't be able to settle down in one place if he tried!