outlier

Etymology

It is formed from English out- + lier,^[2][3] an agent noun from lie, to rest or recline,^[4][5] modelled on the phrasal verb “lie out”.^[6] The OED compares the verb outlie.^[2]

Earliest recorded meaning

A person whose origins, beliefs or behaviour place them outside a community; an outsider: 1606, in the records of the Church of Aberdour in Scotland.^[2] Etymonline instead gives about 1600 for a stone quarried and removed but left unused,^[4] and the OED records a large detached stone or boulder from 1610, in Aberdeen.^[2]

Semantic evolution

In the 17th century the word was used of a person who slept in the open or lived away from his place of business or duty, a sense the OED records from 1652 to 1866;^[2] the 1989 edition of the OED dated it 1676,^[7] and Etymonline dates the meaning “outsider” to the 1680s, especially for one who does not live where he holds office.^[4] From before 1658, chiefly in Scotland, it was also used of an animal living outside an enclosure or away from the herd;^[2] the English Dialect Dictionary records this for Shetland, Ayrshire and Cumberland, and the sense of a stone lying loose in a field for Scotland.^[8] Geology took the word up in 1833, in Lyell's Principles of Geology, for a part of a rock formation cut off from the main body,^[2][4] and since the mid-19th century it has been used of any outlying part detached from the main mass.^[2][4] The statistical sense, an observation that lies outside the expected range of values, is recorded from 1907, in Biometrika.^[2]

Timeline

• 1606 – an outsider, a nonconformist.^[2]
• 1610 – in Scotland, a large detached stone or boulder.^[2]
• 1652 – a person who sleeps in the open or lives away from his place of business (obsolete by 1866).^[2]
• before 1658 – an animal that lives outside an enclosure or away from the herd.^[2]
• 1833 – in geology, a part of a rock formation separated from the main body.^[2][4]
• 1852 – an outlying part of anything, detached from the main body.^[2] Etymonline dates this sense to 1849.^[4]
• 1907 – in statistics, an observation far outside the expected values.^[2]

Meanings

Noun

1. In statistics, an observation whose value differs markedly from the others in a sample: A single outlier pushed the average far above the typical result.^[6][9][2]
2. A person or thing that lies apart from, or is classed differently from, the main or related body; an outsider.^[6][9][2]
3. In geology, a part of a rock formation separated from the main body by erosion and surrounded by older rocks.^[6][2]
4. An outlying island, mountain or other feature of the landscape.^[6]
5. An animal that lives outside the fold or enclosure.^[6][2]
6. A person who lives or sleeps away from his or her place of business or duty.^[6][9]

Related words

• outlie
• outlying
• lie

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
4. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
5. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
6. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
8. ^ Wright, Joseph, ed. (1898–1905), The English Dialect Dictionary, 6 vols., Oxford: Henry Frowde; via EDD Online 4.0, University of Innsbruck (CC BY 4.0)
9. ^ a b c Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster