sundial

Etymology

It is formed from English sun + dial.^[2][3][4] The second element by itself had already meant a sundial in the early 15th century, and it comes from Old French dyal, apparently from Medieval Latin dialis (“daily”), from Latin diēs (“day”).^[5] The name of the shell follows the genus name in scientific Latin, itself a specific use of sōlārium (“sundial”).^[2]

Earliest recorded meaning

An instrument that tells the time by a shadow falling on a marked surface: 1555, in L. Digges's Prognostication of Right Good Effect.^[2] This antedates the 1570s of Dictionary.com^[3] and the 1599 of Merriam-Webster.^[6]

Semantic evolution

Johnson (1755) defined it as a marked plate on which the shadow points the hour, and quoted Donne and Locke.^[4] The OED records a transferred use from 1868, for tropical marine snails of the family Architectonicidae, more fully called sundial shell.^[2] In the eastern United States it is also a name for a wild lupine, called so because its leaves tilt up to 90 degrees to follow the sun.^[6]

Timeline

• 1555 – an instrument for telling the time by a shadow.^[2] Merriam-Webster's first date is 1599.^[6]
• 1868 – a tropical marine snail with a coiled shell, the sundial shell.^[2]

Meanings

Noun

1. An instrument that shows the time of day by the shadow of a gnomon falling on a surface marked with the hours.^[6][7][2]
2. A tropical marine gastropod of the family Architectonicidae, also called a sundial shell.^[2]
3. A wild lupine (Lupinus perennis) of the eastern United States.^[6]

Related words

• dial
• solarium

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
4. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
5. ^ Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
6. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ Collins English Dictionary (2023), Glasgow: HarperCollins