Keratin is the principal matter of fingernails.
keratin definition by Webster's New World
a tough, fibrous, insoluble protein forming the principal matter of hair, nails, horn, etc.
Origin: kerat(o)- plush -in
keratin definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A tough, insoluble protein substance that is the chief structural constituent of hair, nails, horns, and hooves.
Origin: Greek keras, kerāt-, horn; see ker-1 in Indo-European roots + -in.
- ke·ratˈi·nous adjective
keratin - Medical Definition
The American Heritage® Medical Dictionary Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Any of a group of scleroproteins or albuminoids that contain large amounts of sulfur and are the chief structural constituents of hair, nails, and other horny tissues.
keratin - Science Definition
Any of a class of tough, fibrous proteins that are the main structural component of hair, nails, horns, feathers, and hooves. Keratins are rich in sulfur-containing amino acids, especially cysteine. Individual keratin molecules are entwined helically around each other in long filaments, which are cross-linked by bonds between sulfur atoms on different chains. The twining and cross-linking produce strength and toughness.