medicinal infusion
Technical term for a liquid preparation made by steeping plant material or other substances in water, alcohol, or another solvent, used in herbal medicine or pharmacy.
This infusion is made by steeping dried herbs in hot water.
Compound of 浸 (しん, 'soak, immerse') and 剤 (ざい, 'medicine, preparation'). The term is a modern pharmaceutical coinage, likely from the Meiji period or later, modeled after Western medical terminology.