: 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

Examples of THC in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Should a customer arrive to a bar shortly after consuming any sort of THC, and then order a beer, the establishment serving the drink would be held responsible. Alex Malm, Twin Cities, 7 Feb. 2025 These nationwide edibles are made with D9 THC, which is derived from hemp, and not D8 THC, which is derived from weed. Lindsey Bartlett, Rolling Stone, 4 Feb. 2025 In higher doses, THC can actually increase anxiety in some people (yikes!). Matt Rozo, The Mercury News, 23 Jan. 2025 Hemp is defined by federal law as cannabis with less than 0.3% dry weight of delta-9 THC, the main component that gets users stoned. Robert McCoppin, Chicago Tribune, 18 Jan. 2025 See all Example Sentences for THC 

Word History

Etymology

tetrahydrocannabinol

First Known Use

1967, in the meaning defined above

Time Traveler
The first known use of THC was in 1967

Dictionary Entries Near THC

Cite this Entry

“THC.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/THC. Accessed 15 Feb. 2025.

Medical Definition

: 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

More from Merriam-Webster on THC

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