tropic

Etymology

It is inherited from Middle English tropik, also tropike and tropick,^[2] borrowed from Middle French tropique, also tropicque,^[3][4] and directly borrowed from Late Latin tropicus, used as a noun for a solstitial point.^[3][4][5] The Latin adjective tropicus (“of a turn, of the solstice”)^[6][5] is from Ancient Greek τροπικός (tropikós, “of a turn or change; of the solstice”),^[3][5][4][7] which as a noun, short for τροπικὸς κύκλος (tropikòs kúklos, “tropic circle”), meant the solstice.^[5][3] It is formed from τροπή (tropḗ, “a turning”) and the suffix -ικός (-ikós),^[3][6] from τρέπω (trépō, “to turn”),^[6][8][9] from Proto-Indo-European *trep- (“to turn”).^[5][10] The same Greek noun is the source of trope and trophy.^[11][4] French, Spanish, Portuguese and Italian borrowed the Latin word as well: French tropique, Spanish trópico, Portuguese trópico and Italian tropico.^[3]

Earliest recorded meaning

In astronomy, either of the two signs of the zodiac, Cancer and Capricorn, or the points where the sun appears farthest from the equator: in 1391 Chaucer's Treatise on the Astrolabe says that the sign of Cancer "is clepid the tropik of somer", explaining the word by Greek tropos, "agaynward".^[2][3][4] Etymonline dates the word to the late 14th century.^[5]

Semantic evolution

The idea behind the word is the sun's "turning back": at the solstices it reaches its farthest point north or south of the equator and then appears to return.^[5][11][12] In medieval astronomy the tropic was that turning point itself; from the early 16th century it was also the circle on the celestial sphere that touches the ecliptic there.^[3][13][14] From about 1527 the word was applied in geography to the two corresponding parallels of latitude on the earth, the tropic of Cancer and the tropic of Capricorn,^[3][4][5] and in the plural, from 1598 in the OED, to the hot region between them;^[3] Etymonline and Hoad date this use of the tropics only to the early 19th century.^[5][13] From 1600 the tropics also stood figuratively for great heat or luxuriant growth,^[3] while between about 1594 and 1836 a tropic could be a limit or turning point in general.^[3][14] Separately, through the Greek and Latin senses "figurative", the plural tropics was rarely used for figures of speech, or tropes (1697).^[3] The adjective, first used of the solstices in astronomy (1556), came to mean simply "tropical".^[3][14][6]

Timeline

• 1391 – either of the signs Cancer and Capricorn, the sun's turning points, in Chaucer's Treatise on the Astrolabe.^[3][2][4]
• c. 1450 – either of the two solstitial points on the celestial sphere.^[3]
• 1503 – either of the two circles of the celestial sphere touching the ecliptic at the solstitial points.^[3]
• before 1527 – either of the corresponding parallels of latitude on the earth.^[3][4]
• 1556 – adjective, of or relating to the solstices or the tropics, in astronomy.^[3]
• c. 1594 – figuratively, a turning point or limit (obsolete by 1836).^[3]
• 1598 – the tropics, the region between those parallels.^[3] Etymonline dates this use to 1817.^[5]
• 1600 – figuratively, of the heat or rich growth of the tropics.^[3]
• 1624 – adjective, of or occurring in the tropics; tropical.^[6]
• 1697 – plural, figures of speech; tropes (rare).^[3]

Meanings

Noun

1. Either of the two parallels of latitude about 23½ degrees north and south of the equator, the tropic of Cancer and the tropic of Capricorn.^[12][6][3]
2. the tropics: the hot region of the earth between these two parallels; the torrid zone.^[12][6][3]
3. (astronomy) Either of the two corresponding circles on the celestial sphere, which the sun reaches at its greatest distance north or south of the celestial equator.^[12][6][3]
4. (obsolete) Either of the solstitial points.^[6][14]
5. (obsolete, 1594–1836) A limit or boundary; a turning point.^[3][6]

Adjective

1. Of, relating to, or found in the tropics; tropical: tropic heat.^[6][12]

Word family

• tropicbird
• intertropical
• semitropical
• subtropical
• subtropics
• tropical
• Tropic of Cancer

Related words

• trope
• -tropic
• tropism
• tropo-
• trophy
• contrive

Usage notes

Two later adjectives tropic, pronounced with a long o, have separate origins: one in chemistry, in tropic acid (1867), formed from trop- in tropine, after German;^[3][14] and one in biology and physiology, relating to a tropism (1899), formed from the combining form -tropic.^[3][6][14] Collins notes that tropic and the tropics are sometimes written with a capital.^[12]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c Kurath, Hans; Kuhn, Sherman M.; Lewis, Robert E., eds. (1952–2001), Middle English Dictionary, Ann Arbor: University of Michigan Press; online edition ed. Frances McSparran et al. (2000–2018)
3. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z 27 28 29 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
4. ^ a b c d e f g h Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b c d e f g h i j Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
6. ^ a b c d e f g h i j k l Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
9. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ a b Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
12. ^ a b c d e f Collins English Dictionary (2023), Glasgow: HarperCollins
13. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
14. ^ 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