rigidity

Etymology

It is borrowed from Latin rigiditās (“stiffness, the quality of not bending”),^{[2][3][4][5][6]} formed from rigidus (“stiff, hard”), the source of rigid, and the suffix -tās.^[2][4] The adjective is from rigeō (“to be stiff”),^[3][7] which Etymonline and the American Heritage Dictionary trace to Proto-Indo-European *reig- (“to stretch, be stiff”).^[3][7] The Latin noun is used by Vitruvius, and in post-classical Latin it also meant severity.^[2] The OED compares French rigidité, recorded in the sense "severity, intransigence" from 1641 and in the sense "stiffness" only from the second half of the 18th century;^[2] Johnson derived the English word from the French.^[8]

Earliest recorded meaning

The quality of being rigid; stiffness, hardness: 1607, in E. Topsell's Historie of Foure-footed Beastes.^[2][4] The 1989 edition of the OED had 1624 as its first date,^[9] and Etymonline dates the word to the 1620s.^[3]

Semantic evolution

The figurative sense, strictness or severity, followed in 1620,^[2] and was later applied to systems and rules for the quality of not changing, inflexibility.^[2] Etymonline notes that rigidity tends to be used of physical stiffness, while rigor is the more active or moral word.^[3] In medicine the word meant from 1708 a sustained contraction of the muscles, and later an abnormal resistance of the body to movement.^[2] Johnson (1755) gave two senses: stiffness, especially of the solids of the body, and stiffness of appearance, a lack of easy elegance.^[8] The 19th and 20th centuries added technical senses: in mechanics the modulus of rigidity (1877),^[9] in economics the tendency of wages and prices to stay fixed when conditions change (1896),^[2] and in psychology an inability to adapt one's responses (1925).^[2] The psychological sense is part of a wider pattern of describing the mind in terms of hardness, from the first half of the 20th century.^[10]

Timeline

• 1607 – stiffness, hardness.^[2][4]
• 1620 – strictness, severity; later inflexibility of a system.^[2] Etymonline dates this sense to the 1650s.^[3]
• 1708 – in medicine, a sustained contraction of a muscle.^[2]
• 1877 – modulus of rigidity.^[9]
• 1896 – in economics, the tendency of wages and prices to stay fixed.^[2]
• 1925 – in psychology, an inability to adapt.^[2] The 1989 edition of the OED dated this sense to 1943.^[9]

Meanings

Noun

1. The quality of being rigid; stiffness or an inability to bend: the rigidity of a steel frame.^[4][2][5]
2. In physics and mechanics, resistance to a change of shape, or the measure of it, as in modulus of rigidity.^[3][5][9]
3. Strictness or severity; the quality of rules, opinions or conduct that will not change: the rigidity of the timetable.^[4][2][5]
4. In medicine, abnormal stiffness of the muscles or resistance to movement.^[2]
5. In economics, the tendency of wages and prices to stay fixed despite changing conditions.^[2][4]
6. In psychology, an inability to change in response to circumstances.^[2][5][4]

Related words

• rigid
• rigidness
• rigor

Usage notes

Etymonline, quoting the Century Dictionary, contrasts rigidity, used mostly of physical stiffness, with rigor, which is more active or moral, and puts rigidness between them; it also notes that rigidity is directly opposed to flexibility.^[3]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f g h Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ 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
6. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
8. ^ 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.
9. ^ a b c d e Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
10. ^ Mapping Metaphor with the Historical Thesaurus, University of Glasgow, mappingmetaphor.arts.gla.ac.uk