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

Contains phenylalanine and tryptophan, amino acids with antidepressant properties. —Lindsey Desoto, Health, 5 June 2025

Nine essential amino acids—histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine—are available only through foods or supplements. —Stacey Colino, Time, 27 May 2025

However, because collagen lacks amino acid tryptophan, pairing it with a whey protein is a great way to ensure a full amino acid profile. —Brianna Peters, Vogue, 26 May 2025

Other micronutrients also help support your body’s response to tryptophan and melatonin. —Madeline Holcombe, CNN Money, 23 May 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