: 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.
Guests who book a massage have their choice of regular oil or oil infused with THC and CBD, which can help relax the muscles and reduce inflammation. Tiney Ricciardi, Denver Post, 25 Sep. 2025 Kentucky Hop Water is hopping into the THC beverage market. Maggie Menderski, Louisville Courier Journal, 25 Sep. 2025 Inside his room were some THC edibles and a vial of testosterone. Charles Bethea, New Yorker, 24 Sep. 2025 Reputable brands share exactly how many milligrams of CBD or THC are in each can or bottle. Amy Brightfield, Better Homes & Gardens, 23 Sep. 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

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Cite this Entry

“THC.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/THC. Accessed 1 Oct. 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

Last Updated: - Updated example sentences
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