rationalize

Etymology

It is formed from English rational + -ize.^{[2][3][4][5][6]} The OED compares French rationaliser, recorded from the early 19th century.^[2] The adjective is from Latin ratiōnālis (“of or belonging to reason”), from ratiō (“reckoning, calculation, reason”).^[3]

Earliest recorded meaning

To explain on a rational basis, to make agree with reason: 1665, in N. Hodges.^[2] Merriam-Webster also dates the word to 1665.^[5] The 1989 edition of the OED and Merriam-Webster's Collegiate had 1803,^[7][8] Etymonline gives 1767,^[3] and Dictionary.com 1810–20.^[6]

Semantic evolution

Between 1736 and 1793 the verb could also mean "to endow with reason".^[2] From 1805, in Coleridge, it was used without an object for "to think rationally or as a rationalist";^[2] Etymonline notes that Newman and Browning used it in the sense "to think for oneself, to make reason the supreme test".^[3] From 1816 mathematicians used it for removing irrational quantities from an expression.^[2] Since 1855 it has also meant to explain something away by reason,^[2] as when a myth is given a natural instead of a supernatural explanation.^[8] In 1892 physicists applied it to recasting the units of electromagnetism to remove the factor 4π.^[2] The psychological sense, giving plausible but false reasons for one's own behaviour, usually without knowing it, is recorded from 1913;^[2] the 1989 edition of the OED and Etymonline dated it to 1922, explaining it as making something appear reasonable or socially acceptable.^[7][3] In 1926 the word was applied to reorganizing an industry or business on rational principles to make it more efficient,^[2] since 1969 especially by cutting staff.^[2][9]

Timeline

• 1665 – to explain on a rational basis; to make agree with reason.^[2][5]
• 1736 – to endow with reason (obsolete by 1793).^[2]
• 1805 – intransitive, to think rationally.^[2]
• 1816 – in mathematics, to remove irrational quantities from.^[2]
• 1855 – to explain away rationally.^[2]
• 1892 – in physics, to reformulate the units and equations of electromagnetism.^[2]
• 1913 – in psychology, to justify one's behaviour with plausible but false reasons.^[2] The 1989 edition of the OED and Etymonline dated this sense to 1922.^[7][3]
• 1926 – to reorganize an industry or business to make it more efficient.^[2]
• 1969 – intransitive, to make an organization more efficient, especially by cutting staff.^[2]

Meanings

Verb

1. To justify one's actions, beliefs or feelings with reasons that seem sensible but hide the real, often unconscious, motives: She rationalized the expensive purchase as an investment.^[9][5][2][8]
2. To explain something on a rational basis, or make it agree with reason: to rationalize an old legend.^[5][2][9]
3. To make a business, industry or process more efficient by reorganizing it, especially by removing unnecessary staff or equipment.^[9][2][8]
4. (mathematics) To remove irrational quantities from an expression, as from a denominator.^[9][5][2]
5. (physics) To reformulate the units and equations of electromagnetism so that the factor 4π disappears from those for systems without spherical symmetry.^[2]
6. To think in a rational or rationalistic way.^[2][3]

Word family

• rationalizer
• rationalizable
• rationalization
• overrationalize

Related words

• rational
• ratio
• reason
• rationalism
• rationale

Usage notes

Random House notes that the psychological sense, ascribing one's acts to reasons that seem sound but are not the true ones, has become the commoner meaning, while the older sense "to make agree with reason" survives; context usually shows which is meant.^[10] The spelling rationalise is chiefly British.^[6][9]

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 u v w x y z Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b c Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
7. ^ a b c Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
8. ^ a b c d Merriam-Webster's Collegiate Dictionary (2003), 11th ed., Springfield, Mass.: Merriam-Webster
9. ^ a b c d e f Collins English Dictionary (2023), Glasgow: HarperCollins
10. ^ Random House Webster's Unabridged Dictionary (1999), 2nd ed., New York: Random House