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

In Wisconsin, a person caught driving with any amount of THC can lead to a ticket or criminal charge. —Kelli Arseneau, jsonline.com, 5 Sep. 2025

According to the American Psychological Association, in the 1960s and 1970s, marijuana averaged about 1% THC; today, many products reach 30% and concentrates can hit 90–95%. —Khloe Quill, FOXNews.com, 5 Sep. 2025

The move comes after months of talk about how and to what degree access to consumable THC and hemp products like delta-8 and delta 9 should be reigned in. —Eleanor Dearman, Fort Worth Star-Telegram, 4 Sep. 2025

The possession, sale, or import of THC-containing substances is strictly prohibited in Japan. —CNN Money, 2 Sep. 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