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

Marijuana is cultivated for high levels of THC in its flowers. — ABC News, 3 Oct. 2026

At the time of the blood test, Perez also had in his system THC, the primary psychoactive compound in marijuana, according to the DA’s Office. — Rosalio Ahumada, Sacbee.com, 2 Oct. 2026

Rules should be based on the THC content, while giving hemp farmers and agricultural experts a seat at the table. — Mary Ramsey, Charlotte Observer, 2 Oct. 2026

His blood had contained a hundred and ninety-five nanograms of THC per millilitre, which is thirty-nine times the legal threshold for a driver in Colorado. — Peter Hessler, New Yorker, 28 Sep. 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