outlier
noun [ C ]
uk/ˈaʊtˌlaɪər/ usa fact, figure, piece of data, etc. that is very different from all the others in a set and does not seem to fit the same pattern:
Eliminating one or two obvious outliers, charges range from 0.45% per annum to 3.67% per annum.
The poll that showed him increasing support by 5 points was probably an outlier.