bisect

Etymology

It is formed from English bi- + -sect,^[2][3][4] apparently within English, as the OED says, comparing intersect.^[5] The element -sect is from Latin secō (“to cut”), through its participial stem,^[5][6][7][8] from Proto-Indo-European *sek- (“to cut”).^[9] Etymonline instead derives the verb from New Latin bisectus.^[9] Johnson had derived it from Latin bīnus and secō.^[10]

Earliest recorded meaning

To cut into two equal parts: 1646, in Sir Thomas Browne's Pseudodoxia Epidemica,^[5][6] where "the rational horizon bisecteth the globe into two equal parts", as Johnson quotes it.^[10] Merriam-Webster Unabridged dates the word to about 1645, and Etymonline to the 1640s.^[2][9]

Semantic evolution

The first and usual sense required two equal parts, as it still does in geometry.^[5][4][3] The looser sense, to divide into any two parts, is recorded from 1780, in Bentham.^[5] Johnson (1755) already defined the verb simply as to divide into two parts.^[10] The intransitive use, to divide or fork, is recorded from 1870,^[5] and Merriam-Webster Unabridged and Dictionary.com also have it of roads or railways crossing something.^[2][3] Philatelists use it for cutting a postage stamp in pieces, each worth a fraction of the postage value.^[2] The noun comes from the verb: from 1916, in Clements's Plant Succession, it is a cross-section through soil that shows a plant's parts above and below ground.^[5][2] Merriam-Webster Unabridged also has it for a piece of a bisected stamp.^[2]

Timeline

• 1646 – to cut into two equal parts.^[5][6]
• 1780 – to cut into any two parts.^[5]
• 1870 – intransitive, to divide in two, to fork.^[5]
• 1916 – noun, a cross-section through soil showing a plant's parts.^[5][2]

Meanings

Verb

1. To divide into two equal parts, especially in geometry: Draw a line that bisects the angle.^[4][2][5]
2. To cut or divide into two parts: A river bisects the valley.^[4][5]
3. To cross or intersect, chiefly of roads and railways: The new motorway bisects the old farm track.^[2][3]
4. To split in two; to fork.^[5][3]
5. To cut a postage stamp into pieces, each worth a fraction of its postage value.^[2]

Noun

1. A piece of a bisected postage stamp.^[2]
2. An examination of a plant's parts above and below ground through a cross-section of the soil, or a drawing of its findings.^[2][5]

Word family

• bisection
• bisectional
• bisectionally

Related words

• bisector
• dissect
• intersect
• section
• sector
• secant
• bi-

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
3. ^ a b c d e Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
4. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins
5. ^ a b c d e f g h i j k l m n o Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
6. ^ a b c Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
7. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
8. ^ 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 Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
10. ^ a b c Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.