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

Hemp, which comes from cannabis plants that have minimal amounts of the psychoactive substance tetrahydrocannabinol (THC), can act as a thermal regulator when used to insulate buildings. — Amy Gunia, CNN Money, 24 June 2026

The results of the blood sample allegedly confirmed the presence of THC in her blood, according to the statement. — Kimberlee Speakman, PEOPLE, 18 June 2026

The driver who killed her had a combination of alcohol, THC, cocaine and Xanax in his system, according to the Texas Department of Transportation. — Mary Ella Hastings june 18, Fort Worth Star-Telegram, 18 June 2026

During a search of Getz's vehicle, officers found THC vape pens, and received information that Getz may have used THC on the day of the crash. — Briauna Brown, CBS News, 17 June 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