thermometer

Etymology

It is borrowed from French thermomètre,^{[2][3][4][5][6]} a word first recorded in 1624 and coined by the Jesuit Jean Leuréchon,^[3][5] from Ancient Greek θέρμη (thérmē, “heat”)^[5][4][7][6] or θερμός (thermós, “hot”)^[3][2] and μέτρον (métron, “measure”),^[3][2][5] from Proto-Indo-European *me- (“to measure”).^[3] The OED treats it as a modern formation from the same Greek words,^[8] and the Oxford Dictionary of English also allows New Latin thermometrum as the source.^[9] According to Ayto, the Greek noun goes back to Proto-Indo-European *ghwerm-, which probably also gave warm.^[6] The Latinate name thermoscopium is recorded a little earlier, in the 1610s.^[3][2][8]

Earliest recorded meaning

An instrument for measuring temperature: 1633, in an English translation of Mathematical Recreations.^[8][2][4] Etymonline notes that the earliest such device was Galileo's air thermometer of about 1597, and that the familiar mercury-in-glass thermometer was invented by Fahrenheit in 1714.^[3]

Semantic evolution

Johnson (1755) defined it as an instrument for measuring the heat of the air or of any matter.^[10] The figurative use, for something that shows the state or level of a feeling or opinion, appears in 1801, in Alexander Hamilton.^[8]

Timeline

• 1633 – an instrument for measuring temperature.^[8][2][4]
• 1801 – figurative use.^[8]

Meanings

Noun

1. An instrument for measuring temperature, typically a sealed glass tube with a column of mercury or alcohol that rises and falls along a graded scale.^[11][4][8]
2. (figurative) Something that shows the level or state of a feeling, opinion or condition.^[8]

Word family

• thermometric
• thermometrically

Related words

• thermistor
• thermocouple
• thermometry
• thermostat
• thermal
• warm
• meter
• thermoscope

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c d Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
6. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
7. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
8. ^ a b c d e f g h Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
9. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
10. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
11. ^ Collins English Dictionary (2023), Glasgow: HarperCollins