Merriam-Webster's Collegiate® Dictionary, 11th Edition
MUDDY
I. adjective (muddier; -est)
Date: 15th century
morally impure ; base ,
2. full of or covered with mud, characteristic or suggestive of mud , turbid with sediment,
3. lacking in clarity or brightness ; cloudy , dull , obscure in meaning ; muddled, confused , muddily adverb muddiness noun
II. transitive verb (muddied; muddying)
Date: 1601
to soil or stain with or as if with mud, to make turbid, to make cloudy or dull, confuse