Strict observance of or insistence on traditional correctness, especially of language: "By purism is to be understood a needless and irritating insistence on purity or correctness of speech” ( H.W. Fowler).
An example of purism.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.