THC

:  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 dronabinolb:  one that is present in marijuana only in minute quantities