tryptophan
Americannoun
noun
Etymology
Origin of tryptophan
1900–05; trypto- (irregular combining form representing Greek trīptós “rubbed”) + -phan(e) ( def. )
Explanation
Tryptophan is an amino acid that humans need in their diets in order to be healthy. Meat is known for providing lots of tryptophan. You may be familiar with tryptophan as the chemical present in turkey that is supposed to make people feel like taking a nap after their Thanksgiving feasts. In reality, scientists suspect that carbohydrates and alcohol — as well as overeating — are the true culprits in post-feast sleepiness. Tryptophan is important, though, since it helps our bodies synthesize the protein that we eat.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
It is produced by beneficial gut bacteria when they break down tryptophan, an amino acid found in foods like turkey and nuts.
From Science Daily ● Feb. 8, 2026
Scientists have repeatedly observed disruptions in how tryptophan is processed in aging brains, with even stronger effects seen in neurodegenerative and psychiatric disorders.
From Science Daily ● Jan. 15, 2026
The nutrients are involved in converting tryptophan into the sleep-promoting hormone melatonin, she said.
From The Wall Street Journal ● Dec. 29, 2025
No—they’re football tryptophan, a snoozy bore to watch.
From The Wall Street Journal ● Nov. 24, 2025
Beans have both lysine and tryptophan, but not the amino acids cysteine and methionine, which are provided by maize.
From "1491" by Charles C. Mann
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
