simplify

pelkistää, yksinkertaistaa puhekieltä To make simpler, either by reducing in complexity, reducing to component parts, or making easier to understand.
To become simpler.
2006, Karen Oslund, “Reading Backwards: Language Politics and Cultural Identity in Nineteenth-Century Scandinavia”, in David L. Hoyt and Karen Oslund (editors), The Study of Language and the Politics of Community in Global Context,http://books.google.com/books?id=N8H7YPY4oswC Lexington Books, ISBN 978-0-7391-0955-7, page 126:

Thus, throughout the nineteenth century, linguists generally held that more grammatically complex languages were older and that languages tended to simplify over time—the four grammatical cases of German as contrasted with the seven of Latin, for example.