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

Delta-8 is similar in chemical composition to Delta-9-THC, the psychoactive component in marijuana, and offers a comparatively mild high. —Mary Jane Gibson, Rolling Stone, 16 Nov. 2025

American Shaman, for example, advertises THCa flower with levels up to 36 percent — more than ten times the legal hemp limit once it’s heated and turns into THC. —David Hudnall, Kansas City Star, 14 Nov. 2025

As Congress hurried to end the government shutdown, lawmakers OK’d a provision that prohibits the sale of hemp products with more than just trace levels of THC. —Romy Ellenbogen, Miami Herald, 14 Nov. 2025

Using this product may result in a positive drug screen for THC. —Hannah Kirby, jsonline.com, 14 Nov. 2025

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