serotonin
noun /ˌserəˈtəʊnɪn/
/ˌserəˈtəʊnɪn/
[uncountable]- a chemical in the brain that affects how messages are sent from the brain to the body, and also affects how a person feels
- the feel‐good hormone serotonin
- serotonin—the happiness hormone
Word Origin1940s: from serum + tonic + -in.