thermodynamics

Etymology

It is formed from English thermo- + dynamics,^{[2][3][4][5][6]} after the adjective thermodynamic, with the plural ending -ics used for names of sciences.^[7][3] The adjective was formed from English thermo- + dynamic and is recorded from 1849.^[2][7][6] Thermo-, meaning "heat, temperature", comes from Ancient Greek θερμός (thermós, “hot, warm”),^[7] from Proto-Indo-European *gʷʰer- (“to heat, warm”).^[7] Dynamic is from French dynamique, introduced by Leibniz in 1691, from Ancient Greek δυναμικός (dunamikós, “powerful”), from δύναμις (dúnamis, “power”).^[7]

Earliest recorded meaning

The theory of the relations between heat and mechanical energy and of the conversion of either into the other: 1854, in the Philosophical Transactions of the Royal Society.^[2][7][6] The adjective thermodynamic appears five years earlier, in a paper by W. Thomson in the Transactions of the Royal Society of Edinburgh.^[2]

Semantic evolution

The adjective first meant "operated by the transformation of heat into motive power",^[2][7] and the noun named the science of these relations.^[2] The Century Dictionary remarked, as quoted by Etymonline, that moving forces, though the form of the word suggests them, hardly enter into the subject.^[7] The meaning later widened from heat and mechanical work to the relations between heat and every other form of energy, electrical and chemical too,^[3][8] and the study of large-scale systems through quantities such as pressure and temperature.^[8] It is also used for the thermodynamic processes of a particular system.^[6] Its basic principles are stated as the laws of thermodynamics.^[3][8]

Timeline

• 1849 – the adjective thermodynamic.^[2][7][6]
• 1854 – the science of the relations between heat and mechanical energy.^[2][7][6]

Meanings

Noun

1. The branch of physics that deals with the relations between heat and other forms of energy, and with how one is converted into another (used with a singular verb).^[8][6][3]
2. The thermodynamic processes and behaviour of a particular system (used with a singular or plural verb).^[6]

Word family

• thermodynamicist
• aerothermodynamics

Related words

• thermodynamic
• thermal
• thermometer
• dynamics
• dynamic
• dynamo

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 c d e Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
4. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
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 Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b c d e f g h i j Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins