1) A Score that drags down or improves the average of a group result. Generally a score that is either well below or well above average that will improve or decrease the overall average of the group in question, like an Individual English Class test result.
2) An Australian Indy Rock Band that used that definition to name their band.
1) Zhou is not very good at English and only got 2% during the exams when most others got around 70% which brought the overall average of the class down.
2) The Boys of Outlier had an Ugly Maths Teacher at School and noted that her Ugliness brought down the average hotness of the Female Staff Population at their school.