# phenylalanine

> English word · Noun · IPA /ˌfiːnəlˈæləniːn/ · frequency rank #67,728

## Definitions
1. An essential amino acid C₉H₁₁NO₂ found in most animal proteins; it is essential for growth; the inability to metabolize it leads to phenylketonuria; it is a constituent of aspartame.
2. This molecule or its D-isomer.

## Etymology
From phenyl + alanine.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/phenylalanine