yage: an hallucinogenic psychedelic drink made from the ayahuasca vine of South America.

yeast: a fungus that exists in fruits, some vegetables, soil, and animal excreta; used to ferment carbohydrates, especially sugars, into alcohol and to make bead rise.

yohimbe tree: the source of yohimbine, a stimulant brewed in water as a tea or used in tablet or liquid form as an aphrodisiac.