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

These foods also contain tryptophan, omega-3 fatty acids, and other mood-boosting nutrients. —Lindsey Desoto, Health, 29 May 2026

The other six essential amino acids required to build and repair muscle are histidine, lysine, methionine, phenylalanine, threonine, and tryptophan. —Shimite Obialo, Forbes.com, 26 May 2026

One amino acid found in eggs that’s especially important for immune function is tryptophan. —Mykenna Maniece, Vogue, 8 May 2026

In addition to melatonin, some foods contain tryptophan, an amino acid that can be converted into melatonin in the body, research shows. —The Washington Post, San Diego Union-Tribune, 7 Apr. 2026

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

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