Believe it or not, there’s no technical football term that starts with “J”, except for one that  my husband made up. He uses the term “jamming” to describe the moves the defensive backs put on receivers to keep them from being able to move the ball.  There is either a five or ten yard cushion (Bill can’t remember which) where a DB can put his hands on the receiver and push him around; if he continues to do so after the play moves beyond the cushion, it can result in a holding penalty.  Bill told me there’s probably a proper technical term, but he’s never heard of it.  Obligatory Spaceballs references aside, it works as well as anything else in my opinion.