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

Yes, products that meet the state’s THC limit and follow packaging, labeling and testing requirements can still be sold in Texas. —Tiffani Jackson, Fort Worth Star-Telegram, 13 Mar. 2026

However, a recent Milwaukee Journal Sentinel investigation found that many of these hemp products contain THC above the federal limit. —Gina Lee Castro, jsonline.com, 13 Mar. 2026

Prosecutors say his blood tested positive for THC (10 nanograms per milliliter of blood). —Amanda Lee Myers, USA Today, 10 Mar. 2026

The ordinance will create a new inspection and licensing program for retailers selling tobacco, kratom, and other THC products, with the goal of reducing youth access and usage and protecting kids from tobacco products. —Ashley Portillo, CBS News, 10 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