: 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.
Sales can resume after a judge paused the Ohio governor's ban on THC gummies and beverages. Katie Wiseman, IndyStar, 14 Oct. 2025 Here's what to know about the Ohio ban and what the THC laws are in Kentucky. Marina Johnson, Louisville Courier Journal, 14 Oct. 2025 Multiple students at Princeton Middle School were hospitalized last week after eating THC gummies on school grounds, according to Sharonville police. Brenda Ordonez, Cincinnati Enquirer, 14 Oct. 2025 The store also sells packaged drinks that combine THC and caffeine, which allows users to experience a high without the sleepy effect. Sara Hansen, Denver Post, 13 Oct. 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

Browse Nearby Words

Cite this Entry

“THC.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/THC. Accessed 20 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
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!