unsustainable

Etymology

It is formed from English un- + sustainable, from the negative prefix and the adjective,^[2][3][4] and was first modelled on French insoutenable, which stands in the French passage translated in the first English record (1661 in French).^[2] Merriam-Webster analyses it as un-, sustain and -able.^[5] The OED dates sustainable from 1611, in the sense "bearable",^[2] and Etymonline from the 1610s;^[3] it is formed from the verb sustain, which is from Old French sostenir (“to hold up, bear; to endure”), from Latin sustineō (“to hold up”).^[2][3]

Earliest recorded meaning

That cannot be upheld or defended as valid or true: 1662, in a translation of Antoine Arnauld's New Heresie of the Jesuits.^[2] Etymonline gives "not capable of being sustained" from the 1670s,^[3] and Dictionary.com dates the word to 1670–80.^[4]

Semantic evolution

The word's senses ran ahead of those of sustainable: the OED records sustainable "defensible" from 1680, after unsustainable in that sense,^[2] and sustainable "able to be maintained at a certain rate or level" only from 1924,^[2] although unsustainable had been used of an economic trend that cannot be kept up at its present level or rate since 1830, in M. T. Sadler's Law of Population.^[2] Etymonline dates that sense of sustainable by 1965.^[3] The sense "unbearable", above all over a long time, followed in 1845.^[2] The ecological sense, of activity that exhausts finite natural resources or damages the environment, is recorded from 1975, in the journal Ambio, one year before the matching sense of sustainable.^[2] Collins also records the economists' use for growth that is inflationary.^[6]

Timeline

• 1662 – that cannot be upheld or defended as valid or true.^[2] Etymonline dates the word to the 1670s.^[3]
• 1830 – chiefly of an economic trend, that cannot be kept up at its present level or rate.^[2]
• 1845 – that cannot be endured, unbearable.^[2]
• 1975 – causing ecological damage by using up finite natural resources.^[2]

Meanings

Adjective

1. Not able to be kept up or continued at the same level or rate: an unsustainable pace of borrowing.^[6][2][5]
2. Of development, farming or energy use: depleting natural resources or causing lasting ecological damage.^[6][2]
3. Of economic growth: inflationary.^[6]
4. That cannot be upheld or defended as valid or true: an unsustainable claim.^[2]
5. That cannot be endured for long; unbearable.^[2]

Word family

• unsustainably

Related words

• sustain
• sustenance
• sustainability

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
5. ^ a b Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins