psychoactive

Etymology

It is formed from English psycho- + active.^[2][3][4][5] The OED compares the earlier noun psychoactivity.^[2] The first element goes back to Ancient Greek ψυχο- (psukho-), the combining form of ψυχή (psukhḗ, “soul, mind, spirit”);^[2][3] the second goes back through Old French actif to Latin activus, from actus (“a doing”).^[3]

Earliest recorded meaning

That is the source of mental activity: 1904, in the terminology of the Scottish neurologist and psychiatrist J. Crichton-Browne, in the Edinburgh Medical Journal; this sense was rare and is obsolete.^[2]

Semantic evolution

The word took its current meaning in pharmacology: from 1958 it was used of a drug, or of its properties, able to affect the mind, emotions or behaviour, the same as psychotropic.^[2] Etymonline and Merriam-Webster Unabridged date this sense to 1959,^[3][4] and Dictionary.com to 1960–65.^[5] From 1965 the adjective was also used as a noun for such a drug.^[2][6]

Timeline

• 1904 – that is the source of mental activity (obsolete).^[2]
• 1958 – of a drug, affecting the mind, emotions or behaviour.^[2] Etymonline and Merriam-Webster Unabridged date it to 1959.^[3][4]
• 1965 – noun, a psychoactive drug.^[2][6]

Meanings

Adjective

1. Of a drug or other substance, able to affect the mind, mood or behaviour: Caffeine is a mildly psychoactive substance.^[7][4][2]

Noun

1. A psychoactive drug.^[2][6]

Related words

• psychotropic
• psyche

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k 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 c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ a b c Kay, Christian; Roberts, Jane; Samuels, Michael; Wotherspoon, Irené, eds. (2009), Historical Thesaurus of the Oxford English Dictionary, Oxford: Oxford University Press; online edition (2024)
7. ^ Collins English Dictionary (2023), Glasgow: HarperCollins