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

Some cannabis products are up to 95 percent THC. —Sara Novak, Scientific American, 18 May 2026

Georgia governor has signed a bill that expands the state’s medical cannabis program, easing access to cannabis vapes and removing the THC potency cap. —Dario Sabaghi, Forbes.com, 16 May 2026

Only lower-potency THC, referred to as medical cannabis, is legalized for medical use. —Irene Wright, USA Today, 15 May 2026

But hemp manufacturers quickly figured out how to convert CBD in hemp into THC through a process that involves toxic solvents, creating products that sometimes contain harmful chemicals and that can be more potent than products made from marijuana. —Christopher Osher, ProPublica, 15 May 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