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

Emily Gogol will lead participants through creating THC and CBD tinctures and discuss growing cannabis plants in a backyard or patio situation. —Pedro Moura, Los Angeles Times, 1 May 2026

Recent testing on distillate from one of their potential suppliers showed high levels of delta‑8 THC, a sign that it was likely converted from hemp; products that shouldn't be in Colorado's marijuana market. —Karen Morfitt, CBS News, 30 Apr. 2026

For most medical cannabis patients, THC doses should start low and gradually be increased. —Carey S. Cadieux, The Conversation, 29 Apr. 2026

More than half of Gen Z workers – 51% – use THC during the workday – a rate only slightly lower than the 59% who use it after work. —Jessica Guynn, USA Today, 28 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