The phrase "defensive errors" refers to mistakes made by a team or player while trying to defend their opponent in a sport. These errors can lead to the opposing team scoring points or goals. Full definition
It would be a nice statistic to know how many were conceded because of defensive errors from each wing from last 2 seasons. (therepublikofmancunia.com)
When you make defensive errors, thats when goals get scored against you. (justarsenal.com)
He made 3 defensive errors in 3 early games that we should have won. (justarsenal.com)