monoester UK /ˌmɒnəʊˈɛstə/US /ˈmɑnoʊˌɛstɚ/ noun1 •An ester of a polyhydric alcohol or a polycarboxylic acid containing only a single ester group.Twenty healthy individuals participated in the study and on two occasions consumed the ketone monoester supplement or a placebo after a 10-hour fast. — 2018 formsmonoesters