tryptophan

noun

tryp·​to·​phan ˈtrip-tə-ˌfan 

variants or less commonly tryptophane

ˈtrip-tə-ˌfān 

: a crystalline essential amino acid C₁₁H₁₂N₂O₂ that is widely distributed in proteins

Examples of tryptophan in a Sentence

Recent Examples on the Web

Others can metabolize tryptophan into serotonin, the neurotransmitter that is then converted into melatonin, the hormone that regulates our sleep–wake cycle. —New Atlas, 12 Aug. 2025

Foods high in the amino acid tryptophan (like milk, turkey, chicken, lobster, and certain types of nuts) can also increase lethargy, according to Dr. Ganjhu. —Caroline Tien, SELF, 6 Aug. 2025

To improve your mood, bananas contain tryptophan, which the body converts into feel-good hormone serotonin. —Bethany Thayer, Freep.com, 27 July 2025

Oats have plenty of complex carbohydrates and tryptophan, which helps make and support serotonin and energy regulation. —Dr. Samanta Dall’agnese, CNBC, 18 July 2025

Word History

Etymology

borrowed from German Tryptophan, from tryptisch tryptic + -o- -o- + -phan -phane

First Known Use

1890, in the meaning defined above

Phrases Containing tryptophan

• L-tryptophan

Rhymes for tryptophan

• boffin
• coffin
• offen
• often
• soften

Kids Definition

tryptophan

noun

tryp·​to·​phan ˈtrip-tə-ˌfan 

: an amino acid that is found in many proteins and is necessary for life but cannot be manufactured by the human body and must be obtained in food

Medical Definition

tryptophan

noun

tryp·​to·​phan ˈtrip-tə-ˌfan 

variants also tryptophane

-ˌfān 

: a crystalline essential amino acid C₁₁H₁₂N₂O₂ that is widely distributed in proteins

—abbreviation Trp