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

Smoking or otherwise ingesting THC meant hiding it from your parents, teachers, bosses, or the cops, and that low-level, constant anxiety gave stoner movies their compelling shape. —Alison Foreman, IndieWire, 20 Apr. 2026

Lower-potency products are typically 5 to 10 milligrams per gram of THC, study coauthor Tom Freeman, a professor in the department of psychology and director of the Addiction and Mental Health Group at the University of Bath in the United Kingdom, told me in an email. —Sandee Lamotte, CNN Money, 20 Apr. 2026

Each cannabis product intended for pets cannot contain more than 10 milligram of THC per serving, according to AB 1885. —Angela Rodriguez, Sacbee.com, 17 Apr. 2026

In nine states, CBD and low THC products for medical use are legal, but medical and recreational marijuana is not. —Greta Cross, USA Today, 16 Apr. 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