• (n.) A soapy mixture obtained by treating an essential oil with an alkali; hence, any similar compound of an essential oil.
Sap'o·nul noun [ French saponule , from Latin sapo , -onis , soap.] (Old Chem.) A soapy mixture obtained by treating an essential oil with an alkali; hence, any similar compound of an essential oil. [ Written also saponule .] [ Obsolete]