Thujone is a ketone and a monoterpene that occurs predominantly in two diastereomeric (epimeric) forms: (−)-α-thujone and (+)-β-thujone.

Absinthe is an anise-flavored spirit derived from several plants, including the flowers and leaves of Artemisia absinthium, together with green anise, sweet fennel, and other medicinal and culinary herbs. Historically described as a highly alcoholic spirit, it is 45–74% ABV or 90–148 proof in the US. Absinthe traditionally has a natural green color but may also be colorless. It is commonly referred to in historical literature as la fée verte. While sometimes casually referred to as a liqueur, absinthe is not traditionally bottled with sugar or sweeteners. Absinthe is traditionally bottled at a high level of alcohol by volume, but it is normally diluted with water before being consumed.