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.
Impossible to alter: the unalterable season of bitter cold in Siberia.
- un·alˌter·a·bilˈi·ty, un·alˈter·a·ble·ness noun
- un·alˈter·a·bly adverb