Bitters

Bitters, the name given to a compound prepared from an infusion of bitter or aromatic herbs in spirits of wine. Hop bitters is the most common variety, and is highly thought of by some, as an aid to digestion and a mild tonic. It is to the hop that beer owes its efficacy as a tonic. Other herbs frequently used are the gentian, wormwood, cascarilla, and quassia.