(-)-α-Thujone is a bicyclic monoterpene ketone and a key constituent of the essential oils of several plants, most notably common thuja (*Thuja occidentalis*) and wormwood (*Artemisia absinthium*). It is the principal psychoactive component historically associated with the beverage absinthe. Chemically, it is the (-)-enantiomer of α-thujone, characterized by its distinct, pungent, and herbaceous aroma. Its primary industrial applications are in the flavor and fragrance industries. Due to its characteristic aroma, it is used as a fragrance ingredient in perfumery and cosmetic formulations. It also serves as a flavoring agent in certain food products and alcoholic beverages, although its use is strictly regulated due to safety concerns. Historically, it was a defining component of absinthe, contributing to its purported effects. The compound is subject to significant regulatory restrictions in many countries because of its neurotoxic properties. It acts as a non-competitive modulator of the GABA_A receptor, which can lead to convulsions at high doses. Consequently, its concentration in consumer products, especially foods and beverages, is heavily controlled. Current use is largely confined to trace levels in flavorings and fragrances where its unique sensory profile is desired.