A data point that deviates strongly from a clear trend in the rest of the data. Outliers can be the result of completely unexpected phenomena, and can therefore be very interesting.
Often, however, they are the result of an error or misunderstanding.
Outliers can be tedious to handle in data analysis, and it can sometimes be tempting to discard them.
Before doing so, you should ask your teacher about when it is acceptable to delete an outlier.