intersect

Etymology

It is borrowed from Latin intersectus, the past participle of intersecō (“to cut asunder, intersect”),^[2][3][4][5] or, in the OED's wording, its participial stem intersect-.^[6][7][8] The Latin verb is formed from inter (“between”) and secō (“to cut”),^[6][9][8][7] from Proto-Indo-European *sek- (“to cut”),^[9][10] the root of saw.^[2] Barnhart thinks the English verb probably a back-formation from intersection, modelled on the Latin participle, and Etymonline allows both explanations.^[11][9] Intersection is recorded from 1559, borrowed probably through intersection in Middle French and directly from intersectiō, with an earlier Middle English intersectacioun in Lydgate's “Troy Book” (before 1420).^[11] The noun intersect is from intersectum, the neuter of the past participle.^[6][9]

Earliest recorded meaning

To divide something in two by passing through or lying across it; to cross: 1615, in H. Crooke's anatomy Mikrokosmographia, a Description of the Body of Man.^[6][11][2] Etymonline gives the 1610s.^[9]

Semantic evolution

The verb was first transitive: one line or thing crosses another.^[6] The geometrical use, of a line or surface passing through another so that the two share a point or line, follows in 1646, in Sir T. Browne's Pseudodoxia Epidemica.^[6] Johnson (1755) defined it as "to cut; to divide each other mutually".^[12] The intransitive use, of lines, roads and the like crossing each other, is dated 1847 by Etymonline and 1849 by the OED,^[9][6] and later rare senses include dividing two things by passing between them (Cowper, 1785) and, of a person, coming across someone's path (Carlyle, 1858).^[6] Merriam-Webster also records surveying and shorthand uses: fixing a position by triangulation and writing one stroke across another.^[2] The noun was used once, in 1655, for an insect; the geometrical noun, a point of intersection, appears in 1886.^[6][8]

Timeline

• 1615 – to divide by passing through or across; to cross.^[6][11]
• 1646 – geometry, of a line or surface cutting another.^[6]
• 1655 – noun, an insect (only in this period).^[6][8]
• 1785 – to divide two things by passing between them.^[6]
• 1849 – intransitive, to cross each other.^[6] Etymonline dates this use to 1847.^[9]
• 1858 – of a person, to cross another's path.^[6]
• 1886 – noun, a point of intersection.^[6] Etymonline dates the noun in this sense to 1850.^[9]

Meanings

Verb

1. To pass through or across something, dividing it; to cross: A railway line intersects the valley.^[13][2][6]
2. Of roads, lines and the like, to cross each other: The two avenues intersect at the square.^[13][2][6]
3. In mathematics, to have one or more points in common.^[13][6]
4. In surveying, to fix the position of a point by triangulation.^[2]

Noun

1. In geometry, a point or curve of intersection.^[2][6][8]
2. (obsolete, 1655) An insect.^[6][8]

Word family

• unintersected
• nonintersecting

Related words

• intersection
• section
• sector
• secant
• bisect
• saw

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
3. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
4. ^ Skeat, Walter W. (1911), A Concise Etymological Dictionary of the English Language, new ed., Oxford: Clarendon Press
5. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ a b c d e f g h i j k l m n o p q r s t u Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
7. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
8. ^ a b c d e f Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
9. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
12. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
13. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins