undefined

Etymology

It is formed from English un- + defined, the past participle of define.^[2][3][4][5] Dictionary.com likewise analyses it as the prefix un- added to defined.^[6]

Earliest recorded meaning

Not defined or clearly marked; indefinite: 1611, in John Florio's Italian–English dictionary Queen Anna's New World of Words.^[2] Etymonline dates the word to the 1610s,^[3] Dictionary.com to 1605–15,^[6] and the Shorter Oxford to the early 17th century.^[5]

Semantic evolution

Etymonline records the word applied specifically to words and terms by 1716.^[3] Johnson (1755) defined it as "not circumscribed, or explained by a definition", quoting Locke on doctrines guarded by "obscure, doubtful, undefined words".^[7] The adverb undefinedly is recorded from the early 19th century and the noun undefinedness from the mid 19th century.^[5][8] In logic and mathematics Merriam-Webster Unabridged recognizes an undefined term as one that cannot be described or limited in words, a primitive,^[4] and Wiktionary adds the senses of having no value or no sound meaning within a formal system, as in computing.^[1]

Timeline

• 1611 – not defined or clearly marked; indefinite.^[2][8]
• 1716 – of words and terms, not explained by a definition.^[3]
• early 19th century – the adverb undefinedly.^[5]
• mid 19th century – the noun undefinedness.^[5]

Meanings

Adjective

1. Not clearly defined, marked out or limited; vague or indefinite: Their roles on the committee were left undefined.^[9][4][2]
2. Of a term in logic or mathematics, not capable of being defined in other words; primitive.^[4]
3. In mathematics and computing, having no assigned value or no meaning within a given formal system.^[1]

Word family

• undefinedness

References

1. ^ a b c Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d 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. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
7. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
8. ^ a b Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
9. ^ Collins English Dictionary (2023), Glasgow: HarperCollins