inadequacy

Etymology

It is formed from English inadequate + -acy, after adequacy;^[2][3][4][5] Etymonline describes it as the adjective with the abstract-noun suffix -cy.^[6] The adjective, recorded from 1675, is formed from in-, not, and adequate,^[2][6] which goes back to Latin adaequātus (“equalized”), the past participle of adaequō (“to make equal to, to level with”), from ad (“to”) and aequō (“to make level”), from aequus (“equal, even”).^[6]

Earliest recorded meaning

The quality or condition of being inadequate, insufficiency: Etymonline dates the word to 1764,^[6] while the OED's first record is from 1786, in J. Bonnycastle's Introduction to Astronomy,^[2] Merriam-Webster gives 1787,^[3] and Dictionary.com 1780–90.^[5]

Semantic evolution

The noun was formed in the late 18th century, a century after the adjective inadequate;^[2][6][4] its model adequacy is recorded from 1701 in the OED, but only from 1794 in Etymonline.^[2][6] Besides the abstract sense, insufficiency, it came to be used of a particular instance, a failing or shortcoming, and in the plural, inadequacies.^[7][4][6] It is also used of a person's sense of not being equal to what is required: the Shorter Oxford illustrates the word with a modern quotation on "a sense of inadequacy".^[4]

Timeline

• 1764 – the condition of being insufficient or ineffective.^[6] The OED's first record is from 1786.^[2]

Meanings

Noun

1. The quality or state of being inadequate; insufficiency: the inadequacy of the town's water supply.^[3][7][2]
2. A particular failing, shortcoming or lack: the inadequacies of the old timetable.^[7][4]
3. A lack of competence or ability, or a feeling of not being good enough: a nagging sense of inadequacy.^[4][1]

Related words

• adequate
• inadequate
• adequacy

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ a b c d e f Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b c The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin