An extraction or essence of something, obtained by boiling it down(noun)
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Use "decoction" in a sentence
"The explanation rests in the form in which they consume their coffee, namely the decoction, which is free from the sedative principle of the seed, that undoubtedly resides in the aromatic ingredient "cafeol.""
"Bullokar was also the first compiler to identify the domain of a particular term: the word decoction he described as "a boyling or seething; in Phisicke it signifieth commonly any liquor in which medicinable roots, herbas, seedes, flowers or any other thyng hath beene boyled.""
"Let it dry, crush about this much in the palm of your hand, boil it in enough water to fill the bone cup until the decoction is the color of ripe hay."