diode

Etymology

It is formed from English di- + -ode,^[2][3][4] from Ancient Greek δι- (di-, “twice, doubly”) and ὁδός (hodós, “way”).^[5][4][6] The Oxford Dictionary of English takes the second part as a shortening of electrode.^[7][8] Etymonline traces the Greek prefix to δίς (dís, “twice”), related to δύο (dúo, “two”), from Proto-Indo-European *dwóh₁ (“two”), and calls the origin of hodós uncertain.^[6]

Earliest recorded meaning

As an adjective, "of two ways": 1886, applied by W. H. Preece to a way of working a single telegraph wire so that it carried two messages at once.^[5][9][4]

Semantic evolution

The telegraphic adjective was short-lived.^[4] In 1919 W. H. Eccles used the noun for the simplest thermionic valve, with only two electrodes, a cathode and an anode;^[5][6][2] it was then applied to the semiconductor device that does the same work, a crystal rectifier with two terminals.^[5][2] The diode was the model for the names of valves with more electrodes, such as triode.^[7][6]

Timeline

• 1886 – adjective, of two ways, of a telegraph system.^[5][9]
• 1919 – noun, a thermionic valve with two electrodes.^[5][6][2]
• 20th century – a semiconductor rectifier with two terminals.^[5][2]

Meanings

Noun

1. A semiconductor device with two terminals that lets electric current flow in one direction only, used as a rectifier.^[10][2][11]
2. An electron tube with two electrodes, an anode and a cathode.^[2][11][5]

Word family

• LED
• photodiode
• light-emitting diode
• Zener diode

Related words

• electrode
• anode
• cathode
• triode
• tetrode
• pentode
• heptode
• exodus

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
3. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
4. ^ a b c d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c d e f g h Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
6. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
8. ^ Soanes, Catherine; Stevenson, Angus, eds. (2004), Concise Oxford English Dictionary, 11th ed., Oxford: Oxford University Press
9. ^ a b Kay, Christian; Roberts, Jane; Samuels, Michael; Wotherspoon, Irené, eds. (2009), Historical Thesaurus of the Oxford English Dictionary, Oxford: Oxford University Press; online edition (2024)
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins