\ ˌtē-(ˌ)āch-ˈsē How to pronounce THC (audio) \

Definition of THC

: either of two physiologically active isomers C21H30O2 from hemp plant resin especially : one that is the chief intoxicant in marijuana When a person tokes, eats or vapes cannabis, a wave of THC, or tetrahydrocannabinol, washes into the brain. — Laura Sanders THC, the main chemical component of marijuana, has been shown to reduce nausea and increase appetite in chemotherapy patients. — Andrew Weil THC disappears from blood quickly as it is absorbed in the brain, making blood tests a more reliable measure of recent use but not a great correlate of impairment. — Eliza Gray

First Known Use of THC

1967, in the meaning defined above

History and Etymology for THC


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Cite this Entry

“THC.” Dictionary, Merriam-Webster, Accessed 10 Apr. 2021.

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\ ˌtē-ˌāch-ˈsē How to pronounce THC (audio) \

Medical Definition of THC

: either of two physiologically active isomers C21H30O2 that occur naturally in hemp plant resin or are synthetically prepared:
a : one that is the chief intoxicant in marijuana and is used medicinally

called also delta-9-tetrahydrocannabinol, delta-9-THC

— see dronabinol
b : one that is present in marijuana only in minute quantities

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