Of speech: indistinct, imprecise, sloppy. Of a person: having a drawling or indistinct accent.
1930s; earliest use found in Erskine Caldwell (1903–1987). From mush + mouthed, after mushmouth.
英汉双解词典包含464360条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。