Definition of "decoction"

[I]nſtead of Honey, Rob of Elder, Conſerve of Roſes, or Syrup of Violets; Glyſters, Pedilavia of emollient Decoctions with Nitre; or Elder, Vinegar, or Focus's of the ſame, applied with Sponges behind the Ears, to the Armpits, Groins, Hams, &c. or with Barley-water and a little Roſe-vinegar.

1749, [Thomas Short], “[Of the Symptoms of Fevers, and Their Cure.] 10th, Of Feverish Heat”, in A General Chronological History of the Air, Weather, Seasons, Meteors, &c. in Sundry Places and Different Times; More Particularly for the Space of 250 Years. Together with Some of Their Most Remarkable Effects on Animal (Especially Human) Bodies, and Vegetables. In Two Volumes, volume II, Printed for T[homas] Longman, in Paternoster-Row, and A[ndrew] Millar, in the Strand, pages 512–513

The transition is a keen one, I assure you, from a schoolmaster to a sailor, and requires a strong decoction of Seneca and the Stoics to enable you to grin and bear it.

1851, Herman Melville, Moby Dick, Chapter 1

Poley offered a hot decoction of blackberries, saying: Peace?

1993, Anthony Burgess, A Dead Man In Deptford

Witches and devils no longer threaten you and me. We don’t mind living next door to the harmless lady with her herb garden and decoction still, her black cat and red hair.

1994, Jeanette Winterson, Art & Lies

Even the fixed principles of vegetables, at least some of them, are injured by long decoction. The extractive matter, for instance, gradually absorbs oxygen from the atmosphere, and is converted into a substance nearly insipid and inert.

1804, The Medical and Physical Journal, page 563