THC

noun

ˌtē-(ˌ)āch-ˈsē 

: 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

McAlister submitted a urine test that was positive for THC on July 31, 2024. —Steven Johnson, Fort Worth Star-Telegram, 27 Apr. 2026

The change comes as many states have developed thriving markets for THC — the active ingredient in marijuana. —Bill Chappell, NPR, 23 Apr. 2026

Tetrahydrocannabinol, known colloquially as THC, isn't new. —Hannah Yasharoff, USA Today, 23 Apr. 2026

Officers also seized 227 grams of marijuana, 671 grams of psilocybin mushrooms, and about 11,000 grams of THC hash oil. —Matthew Ablon, CBS News, 20 Apr. 2026

Word History

Etymology

tetrahydrocannabinol

First Known Use

1967, in the meaning defined above

Medical Definition

THC

noun

ˌtē-ˌāch-ˈsē 

: 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