ser‧o‧to‧nin /ˌserəˈtəʊnɪn $ -ˈtoʊ-/
noun [uncountable] technical[
Date: 1900-2000;
Origin: serum + tonic + -in]
a chemical in the body that helps carry messages from the brain and is believed to make you feel happy
[TahlilGaran] Dictionary of Contemporary English ▲