n. heavy pin having a head at one end and the other end being hammered flat after being passed through holes in the pieces that are fastened together

n. ornament consisting of a circular rounded protuberance (as on a vault or shield or belt)

v. direct one's attention on something; "Please focus on your studies and not on your hobbies"

v. hold (someone's attention); "The discovery of the skull riveted the paleontologists"