keyword

Etymology

It is formed from English key + word,^[2][3][4] with key in its figurative sense of something that opens or explains.^[3] The OED notes that in later use the first element may be understood as the adjective key, important.^[2]

Earliest recorded meaning

A word that serves as the key to a cipher or code: 1762, in Jachin and Boaz.^[2][5] Etymonline dates the word to 1807, originally of codes and ciphers,^[3] and Dictionary.com to 1855–60.^[4]

Semantic evolution

From the key to a cipher the word passed to a word chosen to represent the contents of a document in an index or catalogue (1827)^[2] and to a word or idea of special importance, one that explains something (1848).^[2] In information retrieval it became the word picked from a text to indicate its contents, in Etymonline's dating from 1967;^[3] the OED records the attributive use in indexes that list keywords with their context from 1959, in H. P. Luhn's report for IBM.^[2]

Timeline

• 1762 – a word that is the key to a cipher.^[2][5]
• 1827 – a word representing a document's content in an index.^[2]
• 1848 – a word or idea of particular importance.^[2]
• 1959 – attributive, of indexes listing keywords in context.^[2]
• 1967 – a word from a text chosen to indicate its contents, in information retrieval.^[3]

Meanings

Noun

1. A word of particular importance or significance: “Sustainability” was the keyword of the conference.^[6][2]
2. A word used to index or search for a document or information, as in a catalogue or database.^[6][2][5]
3. A word that is the key to a cipher or code.^[6][2][5]
4. A word that illustrates the sound of a letter or symbol, as then for th.^[5]

Related words

• key
• word

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e 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 c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b c The American Heritage Dictionary of the English Language (1992), 3rd ed., Boston: Houghton Mifflin