explanatory

Etymology

It is borrowed from Late Latin explānātōrius (“having to do with an explanation”), recorded in the 5th century,^[2][3][4][5] from explānātus, the past participle of explānō (“to make plain or clear”), the source of explain, with the suffix -ōrius, English -ory.^[2][4][5] Etymonline allows that it may instead have been modelled on the Latin word,^[3] and Johnson (1755) simply derived it from explain.^[6] The OED compares the earlier adjective explanative.^[2]

Earliest recorded meaning

Serving or helping to explain something; containing an explanation: first recorded in 1600, in W. Fulbecke's guide to the study of law.^[2] Merriam-Webster dates the word to 1618,^[5] Etymonline to the 1610s,^[3] and Dictionary.com to 1610–20.^[7]

Semantic evolution

The sense has changed little.^[2][8] Johnson (1755) defined it as containing explanation, quoting Swift on explanatory notes.^[6] From 1694 it was also used of a person ready to explain, a use the OED now calls rare,^[2] though the Shorter Oxford illustrates it with Dickens.^[8] A rare noun, an explanation, is recorded from 1650.^[2]

Timeline

• 1600 – serving to explain.^[2] Merriam-Webster dates it to 1618.^[5]
• 1650 – noun, an explanation (rare).^[2]
• 1694 – of a person, disposed to explain.^[2]

Meanings

Adjective

1. Serving or meant to explain something: The chart came with a short explanatory note.^[5][9][2]
2. Of a person, inclined to give explanations.^[5][8][2]

Word family

• explanatorily
• nonexplanatory
• unexplanatory
• self-explanatory

Related words

• explain
• explanation
• explanative
• plain

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
5. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
6. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
7. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
8. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
9. ^ Collins English Dictionary (2023), Glasgow: HarperCollins