any of a group of organic compounds containing one or more amino groups, -NH2, and one or more carboxyl groups, -COOH. The alpha-amino acids RCH(NH2)COOH (where R is either hydrogen or an organic group) are the component molecules of proteins; some can be synthesized in the body (nonessential amino acids) and others cannot and are thus essential components of the diet (essential amino acids)
WordReference Random House Learner's Dictionary of American English © 2026
a•mi•no ac•id /əˈminoʊ ˈæsɪd/USA pronunciation
n. [countable]
WordReference Random House Unabridged Dictionary of American English © 2026- Biochemistrya compound that is one of the building blocks from which proteins are constructed.
ami′no ac′id, [Biochem.]
- Biochemistryany of a class of organic compounds that contains at least one amino group, –NH2, and one carboxyl group, –COOH: the alpha-amino acids, RCH(NH2)COOH, are the building blocks from which proteins are constructed. Cf. essential amino acid.
- 1895–1900
Collins Concise English Dictionary © HarperCollins Publishers::
'amino acid' also found in these entries (note: many are not synonyms or translations):
alanine
- amino
- amino-acid dating
- aminoaciduria
- aminocitric acid
- aminopeptidase
- archaeometry
- arginine
- asparagine
- aspartic acid
- carboxypeptidase
- carcinoid
- citrulline
- code
- codon
- coenzyme A
- creatine
- cystathionine
- cysteine
- cystine
- dopa
- endopeptidase
- enkephalin
- essential
- essential amino acid
- exopeptidase
- genetic code
- glutamic acid
- glutamine
- glycine
- histidine
- homocysteine
- hydroxyproline
- isoleucine
- leucine
- liquid protein
- lysine
- messenger RNA
- methionine
- molecular clock
- nonsense
- ornithine
- peptide bond
- phenylalanine
- proline
- protease
- sense
- threonine
- transaminase
- transfer RNA