something that lies outside the main body or group that it is a part of, as a cow far from the rest of the herd, or a distant island belonging to a cluster of islands: The small factory was an outlier, and unproductive, so the corporation sold it off to private owners who were able to make it profitable.
someone who stands apart from others of his or her group, as by differing behavior, beliefs, or religious practices: scientists who are outliers in their views on climate change.
Statistics.
an observation that is well outside of the expected range of values in a study or experiment, and which is often discarded from the data set: Experience with a variety of data-reduction problems has led to several strategies for dealing with outliers in data sets.
a person whose abilities, achievements, etc., lie outside the range of statistical probability.
Geology. a part of a formation left detached through the removal of surrounding parts by erosion.Compare inlier.
Obsolete. a person residing outside the place of his or her business, duty, etc.
c.1600, "stone quarried and removed but left unused," from out + lie (v.2). Transferred meaning "outsider" is recorded from 1680s; "anything detached from its main body" is from 1849; geological sense is from 1833.
