Decoctum is a term that is used to describe a liquid that has been reduced through boiling or steeping. Synonyms for decoctum include infusion, tincture, concoction, draught, and brew. Infusion is a method of steeping a substance in liquid to extract its flavor or medicinal properties. A tincture is an alcohol-based extract used in medicine. A concoction is a mixture of various substances, usually used in brewing or cooking. A draught is a dose of medicine or a drink. Brew refers to a liquid that has been made by steeping or boiling ingredients. Overall, these synonyms offer various ways to describe the process of reducing liquid through boiling or steeping.