soapbark

American  

[sohp-bahrk] / ˈsoʊpˌbɑrk /

noun

1. a Chilean tree, Quillaja saponaria, of the rose family, having evergreen leaves and small, white flowers.

2. the inner bark of this tree, used as a substitute for soap.

---

soapbark British  

/ ˈsəʊpˌbɑːk /

noun

1. Also called: quillai.  a W South American rosaceous tree, Quillaja saponaria, with undivided evergreen leaves and small white flowers

2. Also called: quillai bark.  the inner bark of this tree, formerly used as soap and as a source of saponin

3. any of several trees or shrubs that have a bark similar to this

---

Etymology

Origin of soapbark

First recorded in 1860–65; soap + bark ²

Example Sentences

Earlier this year, Osbourn and Keasling published the complete 20-step process by which the soapbark tree makes QS-21, reconstituted in tobacco.

From Science Daily • May 8, 2024

Osbourn had earlier teased out the many enzymatic steps involved in the soapbark tree's production of natural QS-21.

From Science Daily • May 8, 2024

QS-21, a potent adjuvant, is sourced directly from the bark of the soapbark tree, raising concerns about the environmental sustainability of its supply.

From Science Daily • Jan. 26, 2024

The Novavax jab also includes a proprietary compound called Matrix-M, which was developed from the bark of Chilean soapbark trees and further stimulates the immune system.

From Scientific American • Oct. 16, 2023

It has boasted about the potential of a secret proprietary ingredient, Matrix-M, an immune system booster derived from Chilean soapbark trees.

From Salon • Jun. 12, 2022