se·​ro·​to·​nin | \ˌsir-ə-ˈtō-nən, ˌser-\

Definition of serotonin 

: a phenolic amine neurotransmitter C10H12N2O that is a powerful vasoconstrictor and is found especially in the brain, blood serum, and gastric mucous membrane of mammals

Examples of serotonin in a Sentence

Recent Examples on the Web

Vitamin B6: An ingredient needed to produce serotonin, the main neurotransmitter that regulates mood and sleep. Elizabeth Bernstein, WSJ, "The Food That Helps Battle Depression," 2 Apr. 2018 By the 1950s, scientists studying LSD had discovered serotonin, figured out that the human brain was full of something called neurotransmitters and begun inching toward the development of the first antidepressants. Tom Bissell, New York Times, "Michael Pollan Drops Acid — and Comes Back From His Trip Convinced," 4 June 2018 Previous research also showed that changes in levels of the brain chemical serotonin, known to be involved in mood, and which is the key element of SSRIs, can affect amygdala development as well. Alice Park, Time, "Taking Antidepressants During Pregnancy May Lead to Fetal Brain Changes," 9 Apr. 2018 That's because the carbs kick-start the production of serotonin, a hormone that regulates your sleep cycle and relaxes you. Rachel Morris, Woman's Day, "8 Delicious Desserts That Can Help You Sleep Better Than Ever," 27 Aug. 2015 But studies have never proved that depressed people suffer from low serotonin (some do, some have normal levels and others have high levels). Maggie Jones, New York Times, "A Reckoning With an Imperfect Science in ‘Blue Dreams’," 3 Apr. 2018 Progesterone may also influence neurotransmitters like serotonin, which help establish your mood. Zahra Barnes, SELF, "11 Symptoms of Premenstrual Dysphoric Disorder You Shouldn’t Ignore," 6 Feb. 2018 In effect, the drugs increase the concentration of serotonin, another neurotransmitter that fascinated Dr. Carlsson. Harrison Smith, Washington Post, "Arvid Carlsson, Nobel laureate who uncovered a treatment for Parkinson’s, dies at 95," 2 July 2018 These are thought to increase feel-good neurotransmitters like serotonin and dopamine, Stepita says. Stephanie Eckelkamp, Good Housekeeping, "9 Tips For Keeping Your Pet Calm And Safe During Fireworks," 30 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'serotonin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of serotonin

1948, in the meaning defined above

History and Etymology for serotonin

sero- + tonic + -in entry 1

Keep scrolling for more

Learn More about serotonin

Statistics for serotonin

Last Updated

3 Nov 2018

Look-up Popularity

Time Traveler for serotonin

The first known use of serotonin was in 1948

See more words from the same year

Keep scrolling for more

More Definitions for serotonin


se·​ro·​to·​nin | \ˌsir-ə-ˈtō-nən, ˌser- \

Medical Definition of serotonin 

: a phenolic amine neurotransmitter C10H12N2O that is a powerful vasoconstrictor and is found especially in the brain, blood serum, and gastric mucous membrane of mammals

called also 5-HT, 5-hydroxytryptamine

Keep scrolling for more

More from Merriam-Webster on serotonin

Nglish: Translation of serotonin for Spanish Speakers

Britannica English: Translation of serotonin for Arabic Speakers Encyclopedia article about serotonin

Comments on serotonin

What made you want to look up serotonin? Please tell us where you read or heard it (including the quote, if possible).


full of whispering sounds

Get Word of the Day daily email!

Test Your Vocabulary

Difficult Vocab Quiz

  • the-education-of-achilles-eugne-delacroix
  • Which is a synonym of discomfit?
Spell It

Can you spell these 10 commonly misspelled words?

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!