Longman Dictionary of Contemporary English homepage

Date: 1900-2000
Origin: serum + tonic + -in

serotonin

 noun
     
ser‧o‧to‧nin [uncountable] technical
a chemical in the body that helps carry messages from the brain and is believed to make you feel happy
Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.

Dictionary pictures of the day
Do you know what each of these is called?
What is the word for picture 1? What is the word for picture 2? What is the word for picture 3? What is the word for picture 4?
Click on any of the pictures above to find out what it is called.

Explore our topic dictionary

Browse the dictionary