mudden

From mud +‎ -en.

mudden (third-person singular simple present muddens, present participle muddening, simple past and past participle muddened)

1. (transitive, intransitive) To make or become muddy or muddied
   • 1874, Gentleman's Magazine and Historical Chronicle, volume 13, page 208:

     When the rains descend and the floods come the Ouse swells, muddens, and overspreads the meadows in a methodical manner, doing its overflowing with dismal thoroughness, but conducting itself with persistent respectability, under circumstances which would warrant any other river in roaring and trampling over all that lay in its way.

• Edmund