serotonin

noun

se·​ro·​to·​nin ˌsir-ə-ˈtō-nən 

ˌser-

: 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

Third, identify the chemical reactions (dopamine, serotonin, cortisol) driving your engagement to break the loop. —Jodie Cook, Forbes.com, 31 May 2026

In those situations, levels of stress hormone cortisol drop while those of serotonin and endorphins rise. —Alessandra Signorelli, Vogue, 29 May 2026

Tryptophan is an amino acid—a building block of protein—which your brain uses to make serotonin and melatonin. —Sarah Klein, Time, 28 May 2026

For Happy Vibes, Think Yellow Yellow brings the sunshine in; researchers hypothesize that much like the sun, yellow boosts levels of the happiness hormone serotonin. —Petra Guglielmetti, Better Homes & Gardens, 22 May 2026

Word History

Etymology

sero- + ton(ic) entry 2 or tone entry 1 + -in entry 1, probably after angiotonin, earlier name for angiotensin — more at angiotensin

Note: Term introduced by Maurice M. Rapport, Arda Alden Green and Irvine H. Page in "Crystalline serotonin," Science, vol. 108, Issue 2804 (September 24, 1948), pp. 329-330: "The general behavior of the crystalline substance is suggestive of its homogeneity. We would like provisionally to name it serotonin, which indicates that its source is serum and its activity is one of causing constriction."

First Known Use

1948, in the meaning defined above

Phrases Containing serotonin

• selective serotonin reuptake inhibitor

Rhymes for serotonin

• calcitonin
• digitonin
• melatonin
• kronen
• onan
• phonon
• ronin
• santonin

Medical Definition

serotonin

noun

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

: 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