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

Consumer Demand Is Shifting Toward Functional Cannabinoids The days when THC percentage alone drove purchasing decisions are fading. —Thomas Andersen, Rolling Stone, 2 Apr. 2026

One is a Cochrane review, published in January, that examined the literature on THC efficacy in treating chronic pain — another condition for which medical marijuana is frequently recommended. —Kevin A. Sabet, STAT, 1 Apr. 2026

Oninski was transported to the hospital and tested positive for benzodiazepines, amphetamines, and THC in her blood. —Landon Mion, FOXNews.com, 1 Apr. 2026

Reparations committee members were expected to reconvene on the 2221 Keeney sale and Delta-8 THC tax on April 2 to come to a decision on a recommendation for consideration of additional funding. —Claire Murphy, Chicago Tribune, 31 Mar. 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